On 4/21/04 12:59 PM, in article , "Nousaine"
wrote:

I attended as talk given by Paul Barton (PSB founder) and he does A/B double
blind tests - his comment that anyone was good at this EXCEPT audiophile
journalists - most of them were scared too much of making an "incorrect"
decision.

In my business one of the greatest lessons I learned about sound from
controlled testing was that some things do sound the same and IT'S ALRIGHT.
This as a time when the 'everything makes a difference' merchandising and
journalism was exploding.

The marketing guys have a difficult time to differentiate their products
when it converges the same way. I don't think it is journalism - but life.

I worked designing RF amplifiers for a number of years and the
differentiators were there as well - but different - distortion and
efficiency were the main goals - and the best cost of owenership won.

Regarding the current benchmark that listening tests yeild levels near
guessing when trying to find audible differences:

"You neglected to address: "Experience is also involved".

I maintain that my ability to hear differences has increased over the
years."

Not at all, maybe even more so to the contrary. Many of those in thee
tested population was done among folk who care and have had long
experience with hi fi gear. One often reported test here was the yamaha
vs. pass labs by one so experienced. His datum point is of an experience
more "trained" then among the general population. Your's too could be
added to the population of tested folk, maybe even finding that now
elusive exception to the current benchmark.

Stewart Pinkerton wrote in message news:Elxhc.10834$GR.1339861@attbi_s01...


I cannot say anything about those, but the TA-N88B was the best amp I
have ever heard.

So you keep saying - but have no evidence for. I didn't find it at all
exceptional.

Call it digital or call it switching (I don't care), it operated
completely differently from 'conventional' amplifiers. I am unaware of
any 'HF artifacts'. During the periods it was working (all too short)
I was constantly amazed by its speed and clarity. All transistors used
in class AB have switching distortion as the signal goes from negative
to positive. It is claimed that class A amplifiers sound better
because they are biased all to the positive and thus do not suffer
from this flaw, but I have had very little exposure to class A amps
(at least high-power ones) and from what I heard I am not sure that
there was that much difference, and whether any difference had more to
do with power supplies and higher-quality parts.

Bromo wrote:
On 4/21/04 1:07 AM, in article Kknhc.8765$GR.1105595@attbi_s01, "Norman
Schwartz" wrote:

"Bromo" wrote in message
news:Lplhc.37177$yD1.107791@attbi_s54...

Depends - I have found that tube amps sound different than solid state
amps.
A solid state PA amp sounds different than an amp, such as NAD. A lot of
negative feedback seems to change the sound somewhat as well - and much of
it should be measurable, though I am sure we haven't learned all there is
to
know about audio measurement.

.... and then as for those tube amps, we must know which manufacturer and
vintage of tube you are talking about, right? since tubes don't simply sound
like tubes and then that's the end of the story? and after that, how many
hours were on those tubes, and then of course how long you warmed them up
before listening to music.


Absolutely - I think the human ear can be much more sensitive to our ability
to measure in a lot of cases.

I'm still unclear as to what these cases might be. On the other hand, it's clear
that our measuring instruments can far outperform our senses in many cases,
e.g. discrimination of electrical properties such as resistance, and
acoustical properties such as loudness.

Douglas Self has some interesting thoughts on this topic:

http://www.dself.dsl.pipex.com/ampin...o/subjectv.htm

in particular the section called "the limits of perception".

--

-S.

"They've got God on their side. All we've got is science and reason."
-- Dawn Hulsey, Talent Director

On 22 Apr 2004 00:07:25 GMT, Bromo wrote:

I think the human ear can be much more sensitive to our ability
to measure in a lot of cases.

All the available evidence from controlled listening tests, suggests
that you are wrong. We can measure to 160dB below full scale of any
audio system, we can certainly not hear more than 130dB or so below
the threshold of pain!

Kinda nice, though, since it given EE's like
myself a whole career to try to devise means of closing the gap!

What gap? The gap is the other way...........
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Wed, 21 Apr 2004 23:11:27 GMT, (Michael
Scarpitti) wrote:

I maintain that my ability to hear differences has increased over the years.

And your *evidence* for this is what, exactly?
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Thu, 22 Apr 2004 00:03:28 GMT, Bromo wrote:

On 4/21/04 12:31 PM, in article Elxhc.10834$GR.1339861@attbi_s01, "Stewart
Pinkerton" wrote:

These amps have advantage for roadies, in that they are advantageous
in the kilograms per kilowatt stakes. They have shown *zero* advantage
in sonic transparency - indeed, how could they? Good amp design has
been a done deal for close on two devcades, despite the claims of the
more imaginative 'high enders'.

While it is easy to design a mediocre amplifier, it is difficult, even
today, to design a truly excellent one. This does not matter if it is an
audio amp, amplifier in a cellular base station or TV transmitter.

Try comparing amplifiers in a blind test - say the Yamaha AX-592 and
the Halcro. You'll find that, while the Halcro will *measure* better,
the two amps will *sound* just the same, below clipping. Then check
the prices, and have a good laugh..................

The advantages of digital amplifiers (switch mode) has barely begun - and it
is a matter of will, time and money to make them as good and transparent as
the current class A/AB circuits the define the best we can do currently.

I believe that the current crop of class D amps *are* as sonically
transparent as a good class A/AB amp, except on low impedance loads
where they droop in the treble. This is due to the required output
low-pass filter, but isn't a serious problem in most systems.

--

Stewart Pinkerton | Music is Art - Audio is Engineering

wrote in message news:7jGhc.853$aQ6.153036@attbi_s51...
Regarding the current benchmark that listening tests yeild levels near
guessing when trying to find audible differences:

"You neglected to address: "Experience is also involved".

I maintain that my ability to hear differences has increased over the
years."

Not at all, maybe even more so to the contrary. Many of those in thee
tested population was done among folk who care and have had long
experience with hi fi gear. One often reported test here was the yamaha
vs. pass labs by one so experienced. His datum point is of an experience
more "trained" then among the general population. Your's too could be
added to the population of tested folk, maybe even finding that now
elusive exception to the current benchmark.

'Experience' means learning how a really good system sounds. One
cannot appreciate what is 'not-quite-so-good' until you have heard
'better'. The brain is unable to recognize minor flaws until a system
lacking those is presented to it. Once that happens, the minor flaws
are must easier to discern.

"Stewart Pinkerton" wrote in message
news:4fxhc.40309$ru4.39603@attbi_s52...

The amp is no 'clearer' than dozens of other sonically trasnaparent
amps, although it does have some rather nasty HF artifacts which might
well be audible.

Changed the thread (cables, hearing stuff was getting too long).
I'd be very interested in knowing some of the models that Stewart considers
to be transparent. I'm in the market at the moment for a good second-hand
power amp that won't break the bank.

Stephen

Harry Lavo wrote:

snip

Are you reading my posts, Stephen?Â* I've proposed testing two variables
among three tests.Â* Each variable *IS* tested separately.Â* But since there
are two variables standing between ordinary home sighted evaluative testing
and Tom's quick-switch a-b and a-b-x testing, then two variables must be
segregated and isolateed to bridge the gap.Â* But tested one at a time.
Which is what I am proposing.

Yet another flaw in your little experiment is that you've never explained
how you would compare the ABX test results to the blind "evaluative"
results. This will be impossible to do, because the ABX test has only two
possible answers, and the "evaluative" test has billions.

snip

The "phantom switch" is a deliberate mislead..whether intentional or not.
The subject believes the switch has taken place and is predisposed to hear
differences.Â* However, somebody who is honestly trying to hear differences
between equipment is not necessarily biased in one direction or another by
anything so blatent, so bias if it exists at all may be subtle or even
counter-choice and overridden by actual sound quality.Â* This is a very
different set of circumstances.

Wrong. The subject's state of mind is EXACTLY the same in both cases. In
both cases, he believes he is listening to two different units, and in both
cases his perception is (potentially) biased by that belief. Bias has
nothing to do with what's real and everything to do with what the subject
thinks is real.

snip

Please don't put words in my mouth, or ascribe motivation.Â* The test I've
proposed that should solve controversy once and for all cannot be done by
one person, which is why I am trying to set something up that the group
could participate in.Â* And I will be the first in line once it is set up.

I won't do the conventional testing because it has not been validated,

Ahem. It's the only thing that HAS been validated.

and a
null would mean nothing but cause great glee here on RAHE.Â* And I've never
claimed that wouldn't happen...only that I believe the test is flawed and
if
it happened it might not mean what you folks assume it means.

Aren't we seeing the same thing here in reverse?Â* I'm attempting to
postulate and get started a test to bridge the gap and answere questions,

Well, your questions, anyway. But that's because you simply refuse to accept
the answers that are already out there.

and what I get from you and some others are criticism and carping and
unwillingness to even intellectually acknowledge what I am trying to do.
Much less moving the test forward.

Your agenda, no one else's.

Look, Harry, a week ago you challenged me to stop carping and offer a
constructive contribution. I think I've done that. I've told you exactly why
your experiment is unworkable, and I've even offered a simpler alternative
that would show you, if you'd bother to do it, whether there's any basis for
what you believe. (There isn't, but I do admire a man who wants to learn
things for himself.) Now it's up to you.

bob

__________________________________________________ _______________
Watch LIVE baseball games on your computer with MLB.TV, included with MSN
Premium!
http://join.msn.com/?page=features/m...ave/direct/01/

On 4/22/04 1:47 PM, in article _wThc.3951$YP5.359561@attbi_s02, "Stewart
Pinkerton" wrote:

On Thu, 22 Apr 2004 00:03:28 GMT, Bromo wrote:

On 4/21/04 12:31 PM, in article Elxhc.10834$GR.1339861@attbi_s01, "Stewart
Pinkerton" wrote:

These amps have advantage for roadies, in that they are advantageous
in the kilograms per kilowatt stakes. They have shown *zero* advantage
in sonic transparency - indeed, how could they? Good amp design has
been a done deal for close on two devcades, despite the claims of the
more imaginative 'high enders'.

While it is easy to design a mediocre amplifier, it is difficult, even
today, to design a truly excellent one. This does not matter if it is an
audio amp, amplifier in a cellular base station or TV transmitter.

Try comparing amplifiers in a blind test - say the Yamaha AX-592 and
the Halcro. You'll find that, while the Halcro will *measure* better,
the two amps will *sound* just the same, below clipping. Then check
the prices, and have a good laugh..................

It all depends upon your speakers, the impedances of them, and the amount of
power required to excite the coils (or other transducer) that give the
amplifiers a workout.

I had an old Yamaha system that just would not power the Theils I now own -
and I would have LOVED for it to be adequate.

I have found some differences around some speakers and some amps - how they
sound together. It seems to me, though, that you have to take the least
linear element in a sound reproduction system into account (the speakers)
when judging an amplifier.

The advantages of digital amplifiers (switch mode) has barely begun - and it
is a matter of will, time and money to make them as good and transparent as
the current class A/AB circuits the define the best we can do currently.

I believe that the current crop of class D amps *are* as sonically
transparent as a good class A/AB amp, except on low impedance loads
where they droop in the treble. This is due to the required output
low-pass filter, but isn't a serious problem in most systems.

I am not so sure - I know the potential is there - and I hope you are right,
but I do think, as you said, they aren't quite as capable of driving even
moderately difficult loads just yet.

For me with my 3-4 Ohm speakers, I will have to wait...

On 4/22/04 9:45 AM, in article , "Michael
Scarpitti" wrote:

Stewart Pinkerton wrote in message
news:Elxhc.10834$GR.1339861@attbi_s01...


I cannot say anything about those, but the TA-N88B was the best amp I
have ever heard.

So you keep saying - but have no evidence for. I didn't find it at all
exceptional.

Call it digital or call it switching (I don't care), it operated
completely differently from 'conventional' amplifiers. I am unaware of
any 'HF artifacts'. During the periods it was working (all too short)
I was constantly amazed by its speed and clarity. All transistors used
in class AB have switching distortion as the signal goes from negative
to positive.

Transistors go through the linear (resistive) region when going between the
fully on and fully off state which generates most of their heat. Any sort
of switching noise would be produced at much higher frequencies - and if
properly terminated so as not to affect the load of the amplifier, should
not be audible.

There will be super-audible artifacts, though it should not be normally
audible.

It is claimed that class A amplifiers sound better
because they are biased all to the positive and thus do not suffer
from this flaw, but I have had very little exposure to class A amps
(at least high-power ones) and from what I heard I am not sure that
there was that much difference, and whether any difference had more to
do with power supplies and higher-quality parts.

Class "A" amplifiers do not switch, but remain entirely in the resistive
region of the transistor, but tend to also run rather hot, and last I recall
can only have a maximum of 50% efficiency. (The transistors never turn 100%
on or off in this mode).

On 4/22/04 1:45 PM, in article LwThc.3949$YP5.359523@attbi_s02, "Stewart
Pinkerton" wrote:

On Wed, 21 Apr 2004 23:11:27 GMT, (Michael
Scarpitti) wrote:

I maintain that my ability to hear differences has increased over the years.

And your *evidence* for this is what, exactly?

I would figure that this person is perfectly capable of judging. No need to
be a curmudgeon on this! I have found that with some experience I can be
better at things than without. Why should listening be any different?

"'Experience' means learning how a really good system sounds. One
cannot appreciate what is 'not-quite-so-good' until you have heard
'better'. The brain is unable to recognize minor flaws until a system
lacking those is presented to it. Once that happens, the minor flaws
are must easier to discern."

And so was reported the experience of the yamaha/pass labs guy, to the
extent he thought it a cake walk was he so certain of his experience. He
had access to and experience with the kinds of gear that might appear, and
some did, on stereopiles most advertised, oops sorry, recommended list.
If you too have a similar or greater level of experience, your datum point
might prove interesting and maybe even the exception to the benchmark that
he wasn't. The only answer to the question is not multiple attempts at
restatement of one's feeling about certainity or additional reports of
perception experiences, it is to see where one fits with regard to the
benchmark. Lacking that, we have no basis, nor do you, that your reported
experiences are an exception to the benchmark. It is no longer a pie in
the sky potential kind of thing, now we have a benchmark and all the
informed opinion and experience can thus be easily gauged by it.

On 4/22/04 1:43 PM, in article 2vThc.3944$YP5.358873@attbi_s02, "Stewart
Pinkerton" wrote:

On 22 Apr 2004 00:07:25 GMT, Bromo wrote:

I think the human ear can be much more sensitive to our ability
to measure in a lot of cases.

All the available evidence from controlled listening tests, suggests
that you are wrong. We can measure to 160dB below full scale of any
audio system, we can certainly not hear more than 130dB or so below
the threshold of pain!

Kinda nice, though, since it given EE's like
myself a whole career to try to devise means of closing the gap!

What gap? The gap is the other way...........

I suggest you check out the science of audiology - measurements and
techniques are being developed all the time - and the human ear is a pretty
amazing instrument.

Michael Scarpitti wrote:

I maintain that my ability to hear differences has increased over the years.

It's not black and white. A persons detecting mechanism deteriorates with
age. That's a proven fact. Experience (training) helps, but maturity
provides understanding that the detector is not infinately sensitive and
to thus help recognize when one is chasing their own tail.

"Harry Lavo" wrote:

.....large snips....

"Steven Sullivan" wrote in message

But multiple subjects aren;t necessary to test *your* claims about things
*you*
have heard.


I don't feel the need to prove claims about what I have heard. What I am
trying to do is outline a test that any willing participant of RAHE can
participate in and which together will scientifically answer some key
questions....quick switching versu evaluative, and blind versus sighted
evaluative. That's what I am trying to do. Period.

Pardon my saying so but if an individual is unable to reliably identify a
component under any bias controlled modality I simply don't see how he/she can
work in any "evaluative" mode?

wrote:

"'Experience' means learning how a really good system sounds. One
cannot appreciate what is 'not-quite-so-good' until you have heard
'better'. The brain is unable to recognize minor flaws until a system
lacking those is presented to it. Once that happens, the minor flaws
are must easier to discern."

And so was reported the experience of the yamaha/pass labs guy, to the
extent he thought it a cake walk was he so certain of his experience. He
had access to and experience with the kinds of gear that might appear, and
some did, on stereopiles most advertised, oops sorry, recommended list.
If you too have a similar or greater level of experience, your datum point
might prove interesting and maybe even the exception to the benchmark that
he wasn't. The only answer to the question is not multiple attempts at
restatement of one's feeling about certainity or additional reports of
perception experiences, it is to see where one fits with regard to the
benchmark. Lacking that, we have no basis, nor do you, that your reported
experiences are an exception to the benchmark. It is no longer a pie in
the sky potential kind of thing, now we have a benchmark and all the
informed opinion and experience can thus be easily gauged by it.

Allow me to supply more details about the Sunshine Trials. Steve Zipser
challenged people to come to his store so he could show that he could reliably
identify amplifiers by sound alone by offering to pay the airfare of anyone
who would come.

Steve Maki accepted that challenge. I advised him on what to expect. I guessed
that Zip would be wanting to compare amplifiers where there would be no way to
match levels and that he should bring his own ampliifer with level matching
capability (thus the Yamaha integrated) and that he should be prepared to find
Zipser might be hard to "find" once he got there.

Maki asked me to accompany him as proctor. I agreed. Once we entrapped Zipser
at his place, after no response to several phone calls after finding a note and
locked door after the agreed-upon meeting time, he wanted to compare amplifiers
with no level controls on either. So the Yamaha integrated was introduced as
an alternative.

Later on Zipser invoked the "hang-over" defense. So we gave him another chance
the following day. We also gave his wife and another customer chances. None,
under single listener switchpad or cable swap conditions) was able to reliably
identify those 2 amplifiers under any bias controlled (single/double) blind,
level matched conditions using personally selected program material with no
time limits.

Furthermore it took Maki 2-3 months to get Zipser to cough-up airfare. I paid
my own way.

Steven Sullivan wrote in message news:YpThc.15489$GR.2174755@attbi_s01...


Absolutely - I think the human ear can be much more sensitive to our ability
to measure in a lot of cases.

I'm still unclear as to what these cases might be. On the other hand, it's clear
that our measuring instruments can far outperform our senses in many cases,
e.g. discrimination of electrical properties such as resistance, and
acoustical properties such as loudness.

Douglas Self has some interesting thoughts on this topic:

I have read that it is possible to distinguish by eye two different
tones of grey that cannot be measured as distinct.

Bromo wrote:

I suggest you check out the science of audiology - measurements and
techniques are being developed all the time - and the human ear is a pretty
amazing instrument.

There are those in here that suggest the fundamental empirical basis of
audiology is suspect. Stuff such as 'hearing below threshold,' and other
(to put it kindly) questionable things like that. The ear may be amazing,
but it's not that amazing.

Bromo wrote:
Call it digital or call it switching (I don't care), it operated
completely differently from 'conventional' amplifiers. I am unaware
of any 'HF artifacts'. During the periods it was working (all too
short) I was constantly amazed by its speed and clarity. All
transistors used in class AB have switching distortion as the signal
goes from negative to positive.

Transistors go through the linear (resistive) region when going
between the fully on and fully off state which generates most of
their heat. Any sort of switching noise would be produced at much
higher frequencies - and if properly terminated so as not to affect
the load of the amplifier, should not be audible.

In the moment I'm designing a digital amplifier. There are a couple of hard
to overcome problems associated with it, but these are more EMI
(electro-magnetic interference) related stuff. The switching frequency is so
high, and the edges are so steep, that the radiation has become significant.
At audio frequencies this is dampened easily with the output L-C filter,
which will attenuate the fundamental already more than 60dB(1:1000).

There will be super-audible artifacts, though it should not be
normally audible.

It is claimed that class A amplifiers sound better
because they are biased all to the positive and thus do not suffer
from this flaw, but I have had very little exposure to class A amps
(at least high-power ones) and from what I heard I am not sure that
there was that much difference, and whether any difference had more
to do with power supplies and higher-quality parts.

Class A has less distortion because all output devices stay always in
conducting state regardless of output polarity. A A/B-amp will turn off the
lower transistor(s) when the output is positive, but still works in a linear
region. A digital amp has either transistor fully "on" or "off" just the
time is varied.

Class "A" amplifiers do not switch, but remain entirely in the
resistive region of the transistor, but tend to also run rather hot,
and last I recall can only have a maximum of 50% efficiency. (The
transistors never turn 100% on or off in this mode).

Class A amplifiers continuously dissipate almost the same heat, if they are
driven at 1/100th or at full power. Since music material usually has an
average of 1/20th of the peak value, the efficiency will be only 2% at
*full* volume. Good to heat your room. A class A/B amp will be around 35%
and a digital amp 70-85%. The size of the heat-sinks has to be inversly
proportional to these numbers, that is why the new digital amps come in such
neat enclosures. And this is the big advantage of digital.

--
ciao Ban
Bordighera, Italy

"Bob Marcus" wrote:

Harry Lavo wrote:

snip

Are you reading my posts, Stephen?Â* I've proposed testing two variables
among three tests.Â* Each variable *IS* tested separately.Â* But since there
are two variables standing between ordinary home sighted evaluative testing
and Tom's quick-switch a-b and a-b-x testing, then two variables must be
segregated and isolateed to bridge the gap.Â* But tested one at a time.
Which is what I am proposing.

Yet another flaw in your little experiment is that you've never explained
how you would compare the ABX test results to the blind "evaluative"
results. This will be impossible to do, because the ABX test has only two
possible answers, and the "evaluative" test has billions.

Further Mr Lavo hasn't shown that his evaluative method has any temporal
reliabilty for a single subject or inter-subject reliability on any level
without inter-subject communication.

snip

The "phantom switch" is a deliberate mislead..whether intentional or not.
The subject believes the switch has taken place and is predisposed to hear
differences.Â* However, somebody who is honestly trying to hear differences
between equipment is not necessarily biased in one direction or another by
anything so blatent, so bias if it exists at all may be subtle or even
counter-choice and overridden by actual sound quality.Â* This is a very
different set of circumstances.

Wrong. The subject's state of mind is EXACTLY the same in both cases. In
both cases, he believes he is listening to two different units, and in both
cases his perception is (potentially) biased by that belief. Bias has
nothing to do with what's real and everything to do with what the subject
thinks is real.

This is why the phantom switch should be a dope-slap to anybody truly
interested in finding real, repeatable audible difference whether psychological
(phantom imaging) or physical (acoustical).

IMO everybody who has been an "enthusiast" for any period of time has had this
inadvertantly happen to them more than once. In my case after the 2nd or 3rd
time I simply had to put my "ears" on the line for real. I'm wondering why
every experienced enthusiast ((note that I avoid the term 'audiophile' because
to me I've learned that 'audiophiles' are people who spend valuable resources
(time, energy,money) chasing imagined differences)) hasn't tumbled to the fact
any phantom switch requires the use of bias controls going forward.


snip

Please don't put words in my mouth, or ascribe motivation.Â* The test I've
proposed that should solve controversy once and for all cannot be done by
one person, which is why I am trying to set something up that the group
could participate in.Â* And I will be the first in line once it is set up.

I won't do the conventional testing because it has not been validated,

Mr Lavo hasn't validated his methods either. Not has he shown that any
audiophile other than himself uses the evaluative method. He won't even tell us
what the performance categories he would use would be.

I use a variation of this technique for cases where blind testing is impossible
(with less than several million in resources) and have a set of 35+ categories
we regularly use in Listening Technology testing and I use when reviewing
speakers for magazines.

But it's only useful in cases where blind testing is literally impractical or
impossible (autosound) and when you can show that you can actually reliably
identify products. In the latter case there is simply no reason for evaluative
"evaluation" of a product such an an amplifier or cabling when they are
sonically indistinguishable when you figuratively close your eyes.

Ahem. It's the only thing that HAS been validated.

and a
null would mean nothing but cause great glee here on RAHE.Â* And I've never
claimed that wouldn't happen...only that I believe the test is flawed and
if
it happened it might not mean what you folks assume it means.

Aren't we seeing the same thing here in reverse?Â* I'm attempting to
postulate and get started a test to bridge the gap and answere questions,

Well, your questions, anyway. But that's because you simply refuse to accept
the answers that are already out there.

I believe Mr Lavo has launched a clever argument in an attempt to discredit
extant evidence. It is clever, in that he proposes an 'experiment' to find the
truth, with the assumption that it hasn't already been found, which will quite
difficult to execute AND bases his findings up front on the basis that if it
doesn't verify his already stated hypothesis than the bias-controlled technique
must be "invalid."


and what I get from you and some others are criticism and carping and
unwillingness to even intellectually acknowledge what I am trying to do.
Much less moving the test forward.

Your agenda, no one else's.

Look, Harry, a week ago you challenged me to stop carping and offer a
constructive contribution. I think I've done that. I've told you exactly why
your experiment is unworkable, and I've even offered a simpler alternative
that would show you, if you'd bother to do it, whether there's any basis for
what you believe. (There isn't, but I do admire a man who wants to learn
things for himself.) Now it's up to you.

bob

Bob; it remains an "argument" because Harry and his kind really do not have any
evidence of any kind that supports their position. Some have tried; for example
John Atkinson postulated that sample sizes were too small to provide
statistical evidence of amp sound. So, to his credit, he actually conducted a
3000+ trial experiment (null, by the way.)

I've personally conducted multiple experiments leaving, AFAICT, no stone
unturned in the pursuit of amp/wire sound.

Yet folks like Harry Lavo will "argue" any amount of evidence into the ground
including proposing complicated experiments to show that bias controlled
listening tests don't corroborate open-listening methods with regard to
amp/cable/bit sound.

We already know this. But Harry would like to have a
psuedo-scientific-experiment that shows this is true so he can conclude that
bias-controls mask "real" differences. Or even better, argue long and hard that
no one has ever shown this to be the case....even though the long-suffering
audiophile "proposed." such an experiment.

wrote in message ...
"'Experience' means learning how a really good system sounds. One
cannot appreciate what is 'not-quite-so-good' until you have heard
'better'. The brain is unable to recognize minor flaws until a system
lacking those is presented to it. Once that happens, the minor flaws
are must easier to discern."

And so was reported the experience of the yamaha/pass labs guy, to the
extent he thought it a cake walk was he so certain of his experience. He
had access to and experience with the kinds of gear that might appear, and
some did, on stereopiles most advertised, oops sorry, recommended list.
If you too have a similar or greater level of experience, your datum point
might prove interesting and maybe even the exception to the benchmark that
he wasn't. The only answer to the question is not multiple attempts at
restatement of one's feeling about certainity or additional reports of
perception experiences, it is to see where one fits with regard to the
benchmark. Lacking that, we have no basis, nor do you, that your reported
experiences are an exception to the benchmark. It is no longer a pie in
the sky potential kind of thing, now we have a benchmark and all the
informed opinion and experience can thus be easily gauged by it.


I can tell you that the more expeience you have with really good gear,
the more obvious the flaws of lesser gear appear. As a matter of fact,
the drive to upgrade comes from becoming all-too-familiar with the
deficiencies of one's kit. I owned a pair of Yamaha NS-690 speakers in
the late 70's, and eventually their deficiencies made themselves
apparent. I upgraded to the Rogers Studio 1's, which I retained for 20
years. I became frustrated with the slowness of the mid-range, which
comes through the woofer driver in this model. But the high-end was
superb, as was imaging. I eventually stumbled across a pair of Yamah
NS-1000M's, and the Rogers were sold. Had I not had the long period of
familiarity with the Rogers, it would have been very difficult to
evaluate other speakers. 20 years is a long time. I knew those
speakers inside out. When I brought the NS-1000M's home to compare
them, I knew what to listen for. I listened to see how the NS-1000M's
handled what I considered to be the problem areas for the Studio 1's.

I do not anticipate upgrading these speakers, as it would be a very
costly propositiobn to get anything that could clearly out-pace them.

Upgrading several things often shows a cumulative effect that cannot
be pinned down to just one piece. I can tell you that since I changed
speaker cables, interconnect, and added RF traps, these steps together
have made a noticeable difference.

"Bromo" wrote in message
...
On 4/22/04 1:43 PM, in article 2vThc.3944$YP5.358873@attbi_s02,
"Stewart
Pinkerton" wrote:

On 22 Apr 2004 00:07:25 GMT, Bromo wrote:

I think the human ear can be much more sensitive to our ability
to measure in a lot of cases.

All the available evidence from controlled listening tests,
suggests
that you are wrong. We can measure to 160dB below full scale of
any
audio system, we can certainly not hear more than 130dB or so
below
the threshold of pain!

Kinda nice, though, since it given EE's like
myself a whole career to try to devise means of closing the gap!

What gap? The gap is the other way...........

I suggest you check out the science of audiology - measurements and
techniques are being developed all the time - and the human ear is a
pretty
amazing instrument.

Not really. The ear is as good as it has to be to avoid being eaten.
And even then, only until you're old enough to have reproduced.

Norm Strong

In article Qz0ic.7310$aQ6.733669@attbi_s51,
(Michael Scarpitti) wrote:

Steven Sullivan wrote in message
news:YpThc.15489$GR.2174755@attbi_s01...


Absolutely - I think the human ear can be much more sensitive to our
ability
to measure in a lot of cases.

I'm still unclear as to what these cases might be. On the other hand, it's
clear
that our measuring instruments can far outperform our senses in many cases,
e.g. discrimination of electrical properties such as resistance, and
acoustical properties such as loudness.

Douglas Self has some interesting thoughts on this topic:

I have read that it is possible to distinguish by eye two different
tones of grey that cannot be measured as distinct.

The following link should provide some insight into how good a
measurement device the eye is:

http://web.mit.edu/persci/people/ade..._illusion.html

Please make sure to read the explanation link. Note what it has to say
about the influence of the human brain's post processing systems on
perception. By 'post processing' I mean anything that goes on after the
retina converts incoming light into nerve impulses. You don't ever get
to directly perceive that raw data... instead you perceive the result of
some pretty major (and completely unconscious) processing that not only
affects color perception as seen here, but identifies objects, motion,
etc. It's possible to fool the human vision system at a number of
levels, up to and including the cognitive level (which is how magicians
do their stuff -- they know tricks which get you to not notice what
they're really doing).

Same thing applies to sound perception. You might want to think about
that a little.

P.S. I know none of that actually directly addressed discrimination of
subtly different gray tones. Well, I don't know where you read that,
but IMO it is very unlikely to be true. From experience looking at
grayscale ramps on a computer monitor, just 256 levels (8 bits of
precision) is enough to almost completely eliminate visible banding
(banding means there is sufficient difference between adjacent gray
levels for the eye to notice). Go up to 9 or 10 bits (512 or 1024
levels respectively) and I'm sure banding would disappear entirely. I'm
quite sure we can measure grayscale with a precision better than 10 bits.

--
Tim

On Thu, 22 Apr 2004 23:11:49 GMT, Bromo wrote:

On 4/22/04 1:47 PM, in article _wThc.3951$YP5.359561@attbi_s02, "Stewart
Pinkerton" wrote:

On Thu, 22 Apr 2004 00:03:28 GMT, Bromo wrote:

On 4/21/04 12:31 PM, in article Elxhc.10834$GR.1339861@attbi_s01, "Stewart
Pinkerton" wrote:

These amps have advantage for roadies, in that they are advantageous
in the kilograms per kilowatt stakes. They have shown *zero* advantage
in sonic transparency - indeed, how could they? Good amp design has
been a done deal for close on two devcades, despite the claims of the
more imaginative 'high enders'.

While it is easy to design a mediocre amplifier, it is difficult, even
today, to design a truly excellent one. This does not matter if it is an
audio amp, amplifier in a cellular base station or TV transmitter.

Try comparing amplifiers in a blind test - say the Yamaha AX-592 and
the Halcro. You'll find that, while the Halcro will *measure* better,
the two amps will *sound* just the same, below clipping. Then check
the prices, and have a good laugh..................

It all depends upon your speakers, the impedances of them, and the amount of
power required to excite the coils (or other transducer) that give the
amplifiers a workout.

That's why I specified 'below clipping'.

I had an old Yamaha system that just would not power the Theils I now own -
and I would have LOVED for it to be adequate.

A Rotel 1090 should have no problem driving those.

I have found some differences around some speakers and some amps - how they
sound together. It seems to me, though, that you have to take the least
linear element in a sound reproduction system into account (the speakers)
when judging an amplifier.

I'm not clear what you're trying to say here, it's the non-linearity
of the speaker which makes the amplifier *less* important, since there
are many amps which simply don't have *any* audible nonlinearity -
what Doug Self calls 'blameless'.

The advantages of digital amplifiers (switch mode) has barely begun - and it
is a matter of will, time and money to make them as good and transparent as
the current class A/AB circuits the define the best we can do currently.

I believe that the current crop of class D amps *are* as sonically
transparent as a good class A/AB amp, except on low impedance loads
where they droop in the treble. This is due to the required output
low-pass filter, but isn't a serious problem in most systems.

I am not so sure - I know the potential is there - and I hope you are right,
but I do think, as you said, they aren't quite as capable of driving even
moderately difficult loads just yet.

For me with my 3-4 Ohm speakers, I will have to wait...

I've heard a digital amp work perfectly well on my 3-ohm Duetta Sigs,
but there's no advantage in digtal amps for home use, where size and
weight don't really matter.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On 22 Apr 2004 23:55:55 GMT, Bromo wrote:

On 4/22/04 1:45 PM, in article LwThc.3949$YP5.359523@attbi_s02, "Stewart
Pinkerton" wrote:

On Wed, 21 Apr 2004 23:11:27 GMT, (Michael
Scarpitti) wrote:

I maintain that my ability to hear differences has increased over the years.

And your *evidence* for this is what, exactly?

I would figure that this person is perfectly capable of judging. No need to
be a curmudgeon on this! I have found that with some experience I can be
better at things than without. Why should listening be any different?

I am not being curmudgeonly (that was JJ's specialist field!), I am
simply pointing out that Scarpitti has made numerous claims, but has
offered *zero* reliable and repeatable evidence for any of them.

--

Stewart Pinkerton | Music is Art - Audio is Engineering

On 22 Apr 2004 23:57:03 GMT, Bromo wrote:

On 4/22/04 1:43 PM, in article 2vThc.3944$YP5.358873@attbi_s02, "Stewart
Pinkerton" wrote:

On 22 Apr 2004 00:07:25 GMT, Bromo wrote:

I think the human ear can be much more sensitive to our ability
to measure in a lot of cases.

All the available evidence from controlled listening tests, suggests
that you are wrong. We can measure to 160dB below full scale of any
audio system, we can certainly not hear more than 130dB or so below
the threshold of pain!

Kinda nice, though, since it given EE's like
myself a whole career to try to devise means of closing the gap!

What gap? The gap is the other way...........

I suggest you check out the science of audiology - measurements and
techniques are being developed all the time - and the human ear is a pretty
amazing instrument.

I have been checking it out for about forty years, and my statement
stands. While indeed an amazing instrument, the neurophysiological
capabilities (and hence limits) of the human ear are well-defined.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On 22 Apr 2004 13:45:25 GMT, (Michael
Scarpitti) wrote:

Stewart Pinkerton wrote in message news:Elxhc.10834$GR.1339861@attbi_s01...

I cannot say anything about those, but the TA-N88B was the best amp I
have ever heard.

So you keep saying - but have no evidence for. I didn't find it at all
exceptional.

Call it digital or call it switching (I don't care), it operated
completely differently from 'conventional' amplifiers. I am unaware of
any 'HF artifacts'. During the periods it was working (all too short)
I was constantly amazed by its speed and clarity. All transistors used
in class AB have switching distortion as the signal goes from negative
to positive. It is claimed that class A amplifiers sound better
because they are biased all to the positive and thus do not suffer
from this flaw, but I have had very little exposure to class A amps
(at least high-power ones) and from what I heard I am not sure that
there was that much difference, and whether any difference had more to
do with power supplies and higher-quality parts.

Clearly, you have very little knowledge of the technology, and were
persuaded by advertising puff into believing that the Sony was
technically superior.

Properly designed Class AB amplifiers do *not* exhibit switching
distortion above the noise floor, and have essentially superceded
Class A amplifiers at all quality levels, with only a few 'pseudo
class A' designs such as Krell's plateau biasing still remaining.

Class D amps like the Sony do indeed operate in a quite different
manner, and suffer *appalling* switching distortion, which is why they
have heavy low-pass filtration (aside from it being necessary for
separation of the audio signal from the switching frequency). Check
the signal before this filter, and you'll find that it is very far
from being the clean square-edged pulse train that is shown in
theoretical design books. The spikes and ringing are an inevitable
source of unharmonic artifacts, and frequently find their way into the
output signal - and also into your source equipment, if it is not well
shielded!

They had a *very* brief outing in the late '70s, and were quickly
abandoned until much faster power switches became available. Nowadays,
it is indeed possible to make a much superior class D amp, and many
such designs are appearing, including the *true* 'digital' amplifiers
which do use the S/PDIF digital datastream as their input signal. In
effect, they are power DACs, which the Sony certainly wasn't.

The bottom line is that the Sony was too far ahead of available
technology, and it most certainly *did* have HF artifacts which some
listeners confused with 'clarity', a common enough mistake with any
overbright product. Any contemporary Krell was a decidedly superior
amplifier, and certainly *did* have audibly perfect clarity, which of
course cannot be improved on by anything.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

From: (Michael Scarpitti)
Date: 4/22/2004 9:02 PM Pacific Standard Time
Message-id: Qz0ic.7310$aQ6.733669@attbi_s51

Steven Sullivan wrote in message
news:YpThc.15489$GR.2174755@attbi_s01...


Absolutely - I think the human ear can be much more sensitive to our
ability
to measure in a lot of cases.

I'm still unclear as to what these cases might be. On the other
hand, it's
clear
that our measuring instruments can far outperform our senses in many
cases,
e.g. discrimination of electrical properties such as resistance, and
acoustical properties such as loudness.

Douglas Self has some interesting thoughts on this topic:

I have read that it is possible to distinguish by eye two different
tones of grey that cannot be measured as distinct.

What you read was mistaken.

On Fri, 23 Apr 2004 04:02:56 GMT, (Michael
Scarpitti) wrote:

Steven Sullivan wrote in message
news:YpThc.15489$GR.2174755@attbi_s01...

Absolutely - I think the human ear can be much more sensitive to our
ability
to measure in a lot of cases.

I'm still unclear as to what these cases might be. On the other
hand, it's clear
that our measuring instruments can far outperform our senses in many
cases,
e.g. discrimination of electrical properties such as resistance, and
acoustical properties such as loudness.

Douglas Self has some interesting thoughts on this topic:

I have read that it is possible to distinguish by eye two different
tones of grey that cannot be measured as distinct.

You have read incorrectly - and this has nothing to do with hearing.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Stewart Pinkerton wrote:

Try comparing amplifiers in a blind test - say the Yamaha AX-592 and
the Halcro. You'll find that, while the Halcro will *measure* better,
the two amps will *sound* just the same, below clipping. Then check
the prices, and have a good laugh..................

I would love to do that. But since a place that would carry the Halcro
would not be carrying the Yamaha.

I believe that the current crop of class D amps *are* as sonically
transparent as a good class A/AB amp, except on low impedance loads
where they droop in the treble. This is due to the required output
low-pass filter, but isn't a serious problem in most systems.

Question. Would you recommend the class "D" amp over a similarly priced
A/AB amp?

Stewart Pinkerton
wrote:


On 22 Apr 2004 23:57:03 GMT, Bromo wrote:

On 4/22/04 1:43 PM, in article 2vThc.3944$YP5.358873@attbi_s02, "Stewart
Pinkerton" wrote:

On 22 Apr 2004 00:07:25 GMT, Bromo wrote:

I think the human ear can be much more sensitive to our ability
to measure in a lot of cases.

All the available evidence from controlled listening tests, suggests
that you are wrong. We can measure to 160dB below full scale of any
audio system, we can certainly not hear more than 130dB or so below
the threshold of pain!

Kinda nice, though, since it given EE's like
myself a whole career to try to devise means of closing the gap!

What gap? The gap is the other way...........

I suggest you check out the science of audiology - measurements and
techniques are being developed all the time - and the human ear is a pretty
amazing instrument.

I have been checking it out for about forty years, and my statement
stands. While indeed an amazing instrument, the neurophysiological
capabilities (and hence limits) of the human ear are well-defined.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Indeed. With sufficient training two sound sources such as a left and right
loudspeaker will trick your natural sensory apparatus into "hearing" a source
between the speakers that has no sound generating mechanism.

"I can tell you that the more expeience you have with really good gear,the
more obvious the flaws of lesser gear appear. As a matter of fact,
the drive to upgrade comes from becoming all-too-familiar with the"

snip

"Upgrading several things often shows a cumulative effect that cannot
be pinned down to just one piece. I can tell you that since I changed
speaker cables, interconnect, and added RF traps, these steps together"

Loudspeakers, yes to some degree, amps and wire, the core of the
discussion, not yet demonstrated by the established benchmark.
Upgrading, which I always thought a manipulative misnomer of marketing, in
one or a dozen steps only adds reports of the perception experience to
those already recieved and assigning labels in the process and ending by
holding a view the labels somehow are analogs of reality. To demonstrate
these reports are an exception to the benchmark, a simple listening alone
test will answer.

"Indeed. With sufficient training two sound sources such as a left and
right loudspeaker will trick your natural sensory apparatus into "hearing"
a source between the speakers that has no sound generating mechanism."

I always think about the example above when people say that subjective
listening is not only the best way to hear "differences", but that the ear
is so far and away a more sensitive test tool. Often people respond about
test gear being able to determine various electrical parameters far beyond
that which the ear can here. Auditory science has gone far above the
electrical into the perceptual in understanding how and why we hear
subjectivly because the ear is connected to the brain and that is the
source of the perception process. my favorite example is about the
perception of location, as was the opening paragraph:

Franssen Effect

http://www.parmly.luc.edu/parmly/franssen.html

The link is from a page of such research at:

http://www.parmly.luc.edu/parmly/audio_demos.html

If one wishes, the effects can be duplicated because sound files are
offered to replicate them. When someone responds with a now familiar "you
are claiming it is only happening in my head", you can say it wouldn't be
surprising and is suggested so by such as above. All the perception
examples there occur in the brain only and have no physical reality in the
signals leaving the speakers. The subjective listener would be fully
substantuated in saying "I hear it, I really do and no one can change my
mind".

Timothy A. Seufert wrote:

Same thing applies to sound perception. You might want to think about
that a little.

It's because of how our mind processes data.

Take you driving down the road - you see a stopsign. Now,
our minds are too slow to process every single thing. It
cheats by not "scanning" the entire image in real-time,
but doing what your video game does - textures and geomerty.

It sees:
octagon
red
"stop"
adjust for size.

This way it doesn't store individual images for the most
part, but merely does pattern matching with the millions of
pieces of data in its visual memory.

Our brain then stores the information as a pattern/algorythm.
Remember pattern and not the raw data. Also, this explains why
our memories are "fuzzy" at times - when it doubt, it matches
the closest pattern and does very little error checking.

Specific memories are remembered, but these usually are special
(stressful)events - maybe a few thousand in our lifetime. The
memory requirements are too severe.

What happens with optical illusions is that our minds, even
when we know how it works, still want to default to the easy
setting. It takes lots of concentration or a second look
to double-check if the expected data isn't what we actually
are seeing.

Our hearing works the same - it's able to handle hundreds of
things at once, but it gets sloppy in order to save time and
space. It's easily tricked and overloaded as well.

IE - if we expect a certain sound or think something is better,
it usually is processed as such unless there are glaring
problems.

wrote:

"I can tell you that the more expeience you have with really good gear,the
more obvious the flaws of lesser gear appear. As a matter of fact,
the drive to upgrade comes from becoming all-too-familiar with the"

snip

"Upgrading several things often shows a cumulative effect that cannot
be pinned down to just one piece. I can tell you that since I changed
speaker cables, interconnect, and added RF traps, these steps together"

Loudspeakers, yes to some degree, amps and wire, the core of the
discussion, not yet demonstrated by the established benchmark.
Upgrading, which I always thought a manipulative misnomer of marketing, in
one or a dozen steps only adds reports of the perception experience to
those already recieved and assigning labels in the process and ending by
holding a view the labels somehow are analogs of reality. To demonstrate
these reports are an exception to the benchmark, a simple listening alone
test will answer.

I've tested the serial-tweak-improvement idea before. I once had an on-line
discussion with an experienced audiophile who claimed that a given cable by
itself may not have an audible effect but when combined with other upgrades
they acted in a synergistic fashion. And that removing any one of them would
cause the whole "improvement" system to fail.

I suggested that he use his system and when I would be in New York 2 months
later he could show this to be true when I would substitute an obviously
substandard cable into his system and all he had to do was reliably identify
when the interloper was placed in the system with modest bias-controls
implemented. He initially agreed butu then disappeared about 2 weeks prior to
the visit date.

Some time later I assembled a tweaky system and had 10 seasoned audiophiles
test the tweaks against a decidedly non-tweek system in single subject
non-switched single blind comparisons.

The systems included both included a cd player but the Tweak system had an
outboard DAC with a vacumn tube pre-amp and Bryston power amp, high-end
interconnects and networked speaker cables, resonance/vibration control devices
all with special installation wire dress. No cables touching the floor, and no
AC wires running parallel to signal leads.

The Geak system used the analog outputs from the same CD player, junk-box rca
interconnects, a 25 year old $99 kit solid state preamplifier, a used $200 8
year old solid state power amplifier rated at 100 watts compared to the
250-watt Bryston, 16-gauge autosound speaker cables with a 25-foot section for
one channel and a 6-foot section for the other channel. The 25-foot speaker
cable was also wrapped around the AC cords for the Geak system.

Both system twerminated into a pair of PSB Stratus Mini loudspeakers for which
I had response curves that were taken in the NRC anechoic chamber.

The systems were installed in a ground level full-basement open-joist ceiling
with no reflecting surface other than the ceiling and rear wall (3-feet behind)
within 15 feet of the speakers. There was a large area rug (carpet) on the
floor where the systems were situated. Listeners were placed 6-feet from the
face of the speakers but were free to move the cd player/listening position if
they wished.

Sessions were conducted with as much time as any subject felt necessary to
acquaint himself with the two systems, used their own programs, offered a
refresh at request at anytine during the test, were offered either a flat $20
or a 5 to 1 odds if they wanted to bet $20 of their own, (IOW I would pay them
$100 to their $20 if they scored 9 of 10.)

They all agreed to conduct a minimum of 10 trials and there were no time
limits. They were free to do 3 today and 5 tommorrow and 2 next week. If they
wished. However there would be no payment until a minimum of 10 trials were
accomplished.

There were no limits on the maximum number of trails either. One subject
completed an extra 6 trying to improve his score to 12 of 16.

In the end no subject was able to reliablt identify either of the two systems
in spite of the radical differences between them. My conclusion is that the
serial tweak idea hasn't been validated.

In this test subjects were encouraged to be as "evaluative" as they wanted.
But, quite frankly, the idea that several up-grades work in concert has never
been shown to happen. IOW the idea that several factors with "just below" JND
will combine to produce above threshold effect simply has never been shown to
be true even when subjected to a radically high-level comparison.

Stewart Pinkerton wrote in message news:36cic.8703$0u6.1628422@attbi_s03...
On 22 Apr 2004 23:55:55 GMT, Bromo wrote:

On 4/22/04 1:45 PM, in article LwThc.3949$YP5.359523@attbi_s02, "Stewart
Pinkerton" wrote:

On Wed, 21 Apr 2004 23:11:27 GMT, (Michael
Scarpitti) wrote:

I maintain that my ability to hear differences has increased over the years.

And your *evidence* for this is what, exactly?

I would figure that this person is perfectly capable of judging. No need to
be a curmudgeon on this! I have found that with some experience I can be
better at things than without. Why should listening be any different?

I am not being curmudgeonly (that was JJ's specialist field!), I am
simply pointing out that Scarpitti has made numerous claims, but has
offered *zero* reliable and repeatable evidence for any of them.

What kind of 'evidence' is possible for descriptions of my experience?
How old are you? I am 54. I have owned stereo equipment for more than
30 years. During that time I have made many upgrades. I have also
spent a lot of time listening in audio salons, educating my ear by
listening to some of the very best stuff out there. My current
'system' is the result of rutheless and uncompromising auditions.
Nothing in it is for show. Everything has earned its way in.

On 23 Apr 2004 13:47:52 GMT, (Michael
Scarpitti) wrote:

Upgrading several things often shows a cumulative effect that cannot
be pinned down to just one piece. I can tell you that since I changed
speaker cables, interconnect, and added RF traps, these steps together
have made a noticeable difference.

I can tell you that this will have made no audible difference
whatever, but that would simply bring us right back to square one,
where you will claim that because you hear it, it *must* have real
existence. We have attempted to explain to you why this isn't so, but
to no avail.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Fri, 23 Apr 2004 17:46:13 GMT, TonyP
wrote:

Stewart Pinkerton wrote:

Try comparing amplifiers in a blind test - say the Yamaha AX-592 and
the Halcro. You'll find that, while the Halcro will *measure* better,
the two amps will *sound* just the same, below clipping. Then check
the prices, and have a good laugh..................

I would love to do that. But since a place that would carry the Halcro
would not be carrying the Yamaha.

You can't normally do this in a store, you would need to borrow both
and run the test at home, with your own system.

I believe that the current crop of class D amps *are* as sonically
transparent as a good class A/AB amp, except on low impedance loads
where they droop in the treble. This is due to the required output
low-pass filter, but isn't a serious problem in most systems.

Question. Would you recommend the class "D" amp over a similarly priced
A/AB amp?

Why would I recommend either, unless one were *not* sonically
transparent?
--

Stewart Pinkerton | Music is Art - Audio is Engineering