Why do we want to distortions?


So I read, Tube amplifiers sound better because of the euphonic distortions they add to the music.
I thought we were trying to avoid distortions.  What makes euphonic distortions sound better?
brubin
No doubt when cavemen first beat rhythms on sun bleached mammoth skulls there were rocks and trees lamenting that the sounds-Nature-intended were being distorted for somebody’s subjective euphonic purposes.
And there you have it: Ralph (atmasphere) just gave you a thumbnail version of the master-class in amplifier design he could teach!
like ralph said...

how we hear and how we process good and bad sounds we hear
@atmasphere 

  CH Precision , the 10 serie , has global and local feedback settings.  Is it related with the feedback , you are talking about ?