One of my favorites is a 1962 George Shearing live album on Capitol---San Francisco Scene. As my system resolution has improved over the years, I am able to hear more of the background sounds. More important, however, is Shearing's introduction of a tune "...written by Armando Perraza 15 years ago that he calls My New Mambo." On a really good system, I can "see" Shearing smile as he says "New Mambo." On many systems though this does not come through at all. I think this is a test of not only resolution but also the ability of a system to convey emotion in a recording. I have no idea how to quantitfy that but some systems have it and some don't.