Your mind is pretty well made up that "ultra high-end" amplifiers sound so much better, why bother ask for opinions? Again your post here seems to be pretty much a closed loop. Contrast your post with that of the fellow who bought an Onkyo receiver at a yard sale and is pleasantly surprised at how good it sounds. Listen to what you like and don't fret too much over these questions. If you feel that some distortion, some noise, some non-linearities add to the listening experience, consider yourself part of the new breed of audiophiles who have helped sound reproduction complete the circle. Good day.
neutrality vs. realism
What is actually the final goal of high-end audio: to reproduce recorded music as neutral as possible or to give the highest possible level of realism? For some manufacturers (like Spectral and Madrigal) it is the ultimate goal regarding their amplifiers, to sound like no amplifier at all. There is less coloration, less "house sound", more "truthfulness". I think this is a good basic consideration, but it must not derive the sound of it's musicality. Those amplifiers are generally sounding lifeless! Don't get me wrong, this is not about the tubes vs. solid state controverse at all, because I think that solid state amplifiers are able to give a high level of musicality without sacrificing neutrality (Boulder, FM Acoustics). What seems perfect on paper is not always the way to go: "neutrality" and "perfect measurements" are not the synonyms for musicality and realism.