"Sander deWaal" wrote in message
...
" said:

Your set up sounds more correct than Roberts since inverting would
certainly
present a difference.


Probable differences could also be due to certain phase shifts between
amplifiers, that wouldn't be a problem when using an amp stand-alone,
but might be audible in this setup.

Also, there are inverting and non-inverting amplifiers.
In case of comparing both sorts, one channel has to be inverted first.

--

"Audio as a serious hobby is going down the tubes."
- Howard Ferstler, 25/4/2005

Each amplifier has its' own characteristic, frequency dependent phase shift.
Ideally, a comparison method would allow one to time-delay the compared
signal before nulling, for minimum total power error. After all, an absolute
time shift, constant across the spectrum, has no impact on sound.

With two amplifiers, there are two phase shift curves to deal with. With the
Hafler box, there is one.

Sander, would you like me to scan the documentation and send it to you?