Quote Originally Posted by Quagmire
I'm not talking about amplifier clipping, but in the case of amp clipping, the piercing sound is a result of harmonics, not the output signal itself. The output signal when clipping resembles a square wave which by definition means that the clipped portion of the signal contains no dynamics.

What I am really talking about is an amp compressing the signal before reaching clipping. I'm sure we've all had the experience of playing with the volume on a receiver and up to a certain point, the volume adjustment seems very linear - turn the knob and the music gets proportionately louder. But go beyond a certain point and the volume doesn't respond in such a linear manner any more - the music doesn't get proportionately louder, it just becomes less musical and compressed. Of course, if the volume is turned increasingly higher, the amp will eventually clip which has a completely different sound.

Just posed this a possible cause of what he is hearing.

Q

No. The amp is not compressing. It is the speaker that is compressing. That is the weak link. Never heard of an amp compressing.
Volume controls are not linear throughout is range. And, if at high volume levels he is not getting more volume is certainly different from what he has reported of no volume at all.