I remember spending about 14 year listening to a whole pile of systems - one of my recordings was Beethoven's Moonlight Sonata. (I think from Naxos). Was doing a dealer demo audition to several speakers I requested to audition. I was smart enough to ask him to add another speaker he liked or felt would be best. So he did. within 2 minutes it mopped the floor with the "well reviewed" and "raved" about speakers. And it doesn't need 50 more albums to test. The speaker made the piano sound like a real bloody piano - none of the others did that. If you can't make one instrument sound like a real instrument then how is the fact that it might be a great "soundstaging" speaker going to matter? Yes I can tell that the piano is center and the violin is 3 feet to the left - great - now only if they actually sounded like real instruments would that soundstaging BS actually matter.
The worst dealers are the ones who tell you "The reason the sound is bad is because your rock CD/LP is badly recorded and the greatness of our stereo is telling you how bad it was recorded." Yeah or maybe your stereo sucks and it is ruining my album because of the tipped up treble or lack of driver integration. Many rock/pop albums are compressed - yes - but many systems gut the life and music out of them too - better systems seem to draw the best out of what is there - still tell you it's compressed but doesn't ruin everything.