Originally Posted by beaveav
"That has no meaning, to an EE or to anybody who thinks critically. I was trying to dig a little deeper and find out what is really going on.
In other words, think of it like this: If there is indeed an audible difference, then is must be measurable. So what parameter would account for this difference? Clipping could. A change in FR with level could, though that would be a strange thing to come upon in an amp that was running below clipping. There are probably some other explanations as well.
An EE would understand that driver impedance interacts back with the amplifier. A varying voltage level, presented to a basic solid state amplifier can result in current deficiencies at several frequencies, which has the potential to
impact the end result that you hear. Especially in regards to bass, and often in "soundstage".
Amps measuring the same on a test bench is not a test of "sound". Amps must be hooked up to an infinitely varying load, aka the loudspeaker.
The most obvious correlation is a comparing two different cars traveling on a concrete road. Everyone would acknowledge that both a Ford Fiesta and a Ferrari 458 Italia can easily drive at 100mph on a concrete road. But change that road to a 35degree upward angle (aka a loudspeaker with a difficult Ohm rating), and the Fiesta may never get to 100mph, even though it is designed to got that "fast", i.e. 100wpc.
If you don't hear any difference between amps, that is cool. There are several amps that sound the same to me, too. But to argue that all decent amps measure the same is ignoring the fact that the amp THD distortion measurement, etc., is only one-half of the measurement equation.