Kosst
Golly if I had known this I could have given up years ago and saved myself a lot of work.
The problem I've got with the concept of "perfect" or "zero distortion" amps is that it really doesn't matter. How perfect is that amp with a loudspeaker drawing current all out of phase, pumping power back into the amp, and presenting impedances all over the chart? Is it still putting out that perfect signal?
Golly if I had known this I could have given up years ago and saved myself a lot of work.