Frantz, Isn't a threshold question to ask and to figure out, at least conceptually, what you are trying to achieve?
I think in terms of the three primary objectives of high-end audio:
1) recreate the sound of an original musical event,
2) reproduce exactly what is on the master tape, and
3) create a sound subjectively pleasing to the audiophile.
Out of these three which do you select as your objective?
Ron, I've been thinking a while about your list of three objectives. I think these are quite similar to Jon Valin's which he has described in TAS. #3) is subjective and can not really be argued. #1) is difficult to verify unless one was at the original musical event AND is luck enough to have a recording of that event to then compare it in his own system. #2) seems to be the most challenging objective. What exactly is on a master tape? Are systems so transparent that we can hear this recorded data with no distortion and exactly as originally intended? And even if we think there has been no corruption to the signal, how do we really know that what we hear in our listening rooms is what the mastering engineer heard through his monitors when creating his tape? The speakers, listening space, associated gear, are all different. I suppose, under ideal circumstances, and with extremely advanced technology, the engineer and we can approach hearing different versions or electronic interpretations of exactly what is on the master tape.
For me it is more than simply sounding pleasing, as in #3, because that may or may not sound real and music is not always pleasing. And it is wholly different from #1 and #2 because they are far too difficult to verify.
I think there is at least one more primary possibility or objective in High End audio: that is to attempt to recreate a sound which reminds the listener of what he thinks actual acoustic instruments sound like, alone or in combination with other instruments. Of course, this is dependent upon the listener's own references of those sounds AND they necessarily fall within some wide range, because each instrument sounds different from the next and they are heard in different spaces throughout one's musical experiences.
So, my goal or objective with my system is for it to sound "similar" to what I remember certain instruments sounded like when I heard them from my unique listening position, in a particular hall, at a particular time, using my own ears. I have heard pianos, violins, cellos, voices, horns and percussive instruments many times, in many different venues. There is no absolute sound for these instruments, because they all sound different. There are way too many variables to mention. But, I can tell if the sound of a violin seems real to me. If I can manage to get my system to sound similar to my memory of the range of a violin, based on the many times I have heard one live, my stereo listening experience will be convincing, believable, and very emotionally rewarding. That is my goal.