And this, folks, is why this hobby is in a death spiral. Stupidly expensive gear with adherents that can "hear" all sorts of artifacts and distortions which they focus on to the detriment of enjoying the music. Had a very interesting chat with my 30 year old software engineering son. He questioned why anyone would spend the kind of money high end companies charge to listen to music. His generation looks upon this hobby as a total waste of time and resources, and that is the future of audio. Go to RMAF or any of the other big shows and take note of what you see. For the most part, a bunch of 60 something white guys with more money (sometimes) than sense. Class A, Class A/B, Class D, Class G, ad nauseum.Not sure I agree with all of this. Go to Munich and watch for the young families with strollers and under 30 years men and women. Its quite different in Europe and Asia!
Regarding distortions- anyone can hear distortion since the ear uses higher ordered harmonics to sense sound pressure. Traditional solid state amps are well-known for making such harmonics and being quite audible as harshness and brightness. This is why tubes still exist!
Kids these days buy LPs- hence the revival of the medium- kids keep the music industry alive! Whether they are conscious of it or not, they are hearing something in the LPs that they like as opposed to digital. You don't have to know anything technical to understand that.
I see people of all ages at RMAF and AXPONA but admit that younger people are a minority. What works for kids is the same as it was for us old people- that its relevant to our lives. When they hear music reproduction that sucks they just stick with their earbuds. When the reproduction is good, then they dream of the day when they can have that sound at home. The latter is what happened to a lot of us older audiophiles. The shows are there so the public (and hopefully kids) can feel the dream.
Regarding class D, the carrot on the stick is that a class D output section does not have the same sort of artifact that is imposed by the output section of a traditional solid state amp. The distortion made by the amp is thus caused by the encoding scheme, whatever is needed to drive the encoder (and some comparitors have pretty low input impedances, so this is not a trivial matter) and how much deadtime is needed to keep the output transistors happy. As switching transistors get faster (the current embodiment of speed being GaN devices) the deadtime needed is reduced and with it the distortion of the amp.