Once again, I'll point out your fallacy. Your entire argument must
assert
one of two things:
1) distortion is present in the output of the amplifier - enough to
exceed
human thresholds of detection; OR
2) while there's no distortion present, one can still hear the
difference.

You're implying that (some) amplifiers are perfect. There is no such
thing. *All* amplifiers output a distorted signal. If the testing equipment
can't detect this, then the error is with the testing equipment.

No, I'm implying that ALL amplifiers are "perfect". In car audio, this is
indeed the case. Every amplifier I've benched exhibits this tendency - even
the el cheapo models. The independently conducted bench testing I've seen
on the net of car audio amplifiers even show the same thing (though I have
no way of verifying their methodology). There's absolutely no reason to
believe that these amplifiers, when not driven into clipping, would not be
able to do this. Quite frankly, amplifiers are easy and cheap to build.

Note that by "perfect" I mean that the level of distortion is well below (at
least one order of magnitude) what's considered audible. And, when you
further take into account the masking that occurs due to road noise, the
distortion inherent in your average loudspeaker setup, and the sloppy
transfer function of an automobile, you'll find that levels of distortion
are well below what they need to be.



You've already rejected #2 in your reply to Eddie Runner in this thread.
So
you are therefore claiming that #1 is the case.

No I'm not. See above. However, it's perfectly feasible that some
amplifiers
output a signal that is below the threshold of human hearing to detect
distortion, and also below the threshold of current measuring devices.

Just in case you're still unclear about this point, the threshold of current
measuring devices is waaaaaay below the threshold of human hearing.


Yet, when one measures the
distortion content of the two amplifiers, there's none to be found
(certainly far less than what is audible to humans).

Which is it? None, or less that what is audible to humans?

Fractions of a percent. I consider that to be none. It's insignificant.

Again, if you can't
measure distortion, then your equipment isn't good enough.

My equipment is good enough. I can create a signal with a tiny level of
distortion and then measure it with this equipment. Therefore, it's good
enough. An alternative technique that serves to eliminate the test
equipment as the culprit is to subtract the measured signal from the input
signal. When you do this, you'll find that the result is essentially zero.
I suggest you give this a try.

Again, there is no
such thing as a perfect amplifier. Hell, there is no such thing as a
perfect
*wire*. The signal will change.

Yep. But it's too small to be audible. So, by psychoacoustical standards,
it's perfect.


Your reasoning has been that the test equipment is wrong. That's a cop
out
if I've ever heard one. Measuring voltage is not rocket science.

Measuring voltage to infinite limits is beyond rocket science.

Why would infinite limits ever be necessary?