inna,
Good point about different conductors. I have several versions of the Beethoven symphonies, some seem to be faster (though the track times are not), some seem more "dynamic" than others, etc.
When I was visiting dealer after dealer, auditioning speakers, it really bugged me when I'd bring in a stack of CDs for my audition and the dealer insisted on demoing with music I would never listen to, but that made the speakers shine. I'd deliberately include a few older CDs, back in the day when the mastering equipment was not the best, to make sure I'd be able to listen for extended periods of time; I could not make it thru the first track of the original "Born to Run" CD, as the "highly resolving" system being demonstrated brought out all the rough edges in a way that was not at all pleasing.