There is a great amount of truth in what you say. As my sainted mother used to say, "'Every one to their own taste', said the old lady as she kissed the cow." There are also things like the placebo effect. And there is a big variation in the hearing acuity of various people. Due to a common old service injury, I am now losing my hearing to the point where I have to use hearing aids in both ears to help understand speech. But for music listening I have to remove the aids. And I am still busily designing sound systems. I used to make a lot of distortion measurements (total distortion is easy to measure). The distortion levels got so low that I couldn't measure them anymore with my dated equipment. My original question was why only single ended triode amps when push pull triode had lower distortion. -Dick