I have had my hearing tested many times over the years. What level of SINAD is audible? Depends on all manner of variables - sleep, listening time, fatigue, etc. Separating what I actually hear from what I think I hear? If you "think" you hear something it may be logically indistinguishable from actually hearing it. But your comments, while theoretically valid, just don't inform my daily experience of listening. Do you know what level of SINAD is audible to you? At all times - under all conditions? It's a silly question to me. Amps are only "good" or "bad"? A bit reductive and simplistic perhaps (responding to another thread). What I see more than anything else here, in the responses, is a tendency to the objectivist desire to be right. A bit totalitarian in flavor. The bottom line - buy what you like. Doesn't matter a whit to me if I like a piece of gear that doesn't measure "up to" another piece whose presentation I find less engaging, i.e., musical, and for whatever reason. To deny the interplay of subjective appreciation with objective metrics is, I think, at best, uninformed.