What I've always heard is that SS produces odd order harmonic distortions (3rd,5th, etc) while tubes produce even order distortions (2nd, 4th, etc). I've also heard that musical instruments produce even order harmonic distortions, which is why most folks find tube equipment more "musical" or "natural", because it's distortions are more similar to that heard from a musical instrument.
What determines good distortion?
I have a friend using an Audio Research CA 50 integrated amp with 45 watts/channel into Vandersteen 2ce sig II. I use a 50 watt YBA integrated into the same speakers. We both listen at sane levels in small rooms 8 x 12. He thinks that it's better to use a 50 watt tube amp rather than a 50 watt SS amp because tubes when they distort sound more pleasant. I'm thinking that if you drive the amp into clipping it's bad with either a SS or tube amp because clipping distortion is bad whether or not you can tolerate it. Am I wrong?