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
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 ?

Thank you for your comments.  but what I am trying to understand is if the original recording is with  euphonic distortions that are deemed as positive then don't we want the most transparent system to hear the original   and   How does tube  euphonic distortions add a stage to the sound?