Better Audio with or without NFB (Negative Feedback) - for me the wrong Question

[tiefbassuebertr]

in this case this thread is also subject to this topic:
http://www.diyaudio.com/forums/solid-state/201033-zero-negative-feedback.html

 

[tiefbassuebertr]

the clear evidence of the accuracy of my statement in post #1 I would need to know, how the THD/IM spectrum looks, if we have the following waveforms:

1) perfect triangle instead of a perfect sine wafe
2) perfect sawtooth instead of a perfect sine wafe
3) a perfect square wave instead of a perfect sine wafe (this spectrum must be similare to that of a clean clipping amplifier without overshooting peaks)

If I know this, I could recognize rspect. guess the source of the distortion spectrum of an unknown amplifier, what design errors were made and from where are this comes.

Perhaps one members can post this typical spectrums

Obviously this seems to be more difficult when I first assumed.