"Wylie Williams" wrote in message
news:JnGXa.68209$o%2.33604@sccrnsc02

AFAIK, some time ago, Jim Johnston of AT&T labs (IMO highly
conservatively) put the point of non-existent returns at -100 dB.
This corresponds to 0.001% distortion.

IME, when frequency response is +/- 0.1 dB 20-20 KHz and all forms of
nonlinear distortion are below 0.01% (as equipment is actually used)
hearing differences due to that equipment in even critical studio or
home use is impossible.

As a practical matter, 0.3 dB frequency response variations and 0.1%
nonlinear distortion is generally impossible to hear in typical home
or studio use.

In casual listening, 1 dB frequency response variations and 1%
nonlinear distortion will usually pass for sonically perfect.

Thanks for the information. It's beginning to look like the main
concern would be deciding how much power is needed.

Yes, you want to avoid clipping. I see the business of buying power amps as
being a three step process.

(1) First one disabuses oneself of the idea that there are *magic* power
amps, IOW one needs to unlearn the idea that there is some indefinable
something that makes one magic power amp sound a lot better than lesser amps
that look similar on paper. The ultimate sin is not failing to buy that one
good-sounding power amp in the whole universe.

(2) Then one realizes that ultimate sin is instead, running out of power.

(3) Sometimes one finds that having a power amp that is so powerful that it
makes destroying speakers too easy can be a bad thing.