Every one of the above posters has given descriptions that are right on the money. The interesting part of all these discussions is that it leads me to conclude what I have intuitively known all along. The room and the equipment become one and the real difference is between ones ears. People have preferences for everything from colors to human features. I've always wondered if the blue I see is the same color inside another persons head. I also wonder the same thing about sound.
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.