Well, with any speaker you are looking at seriously purchasing, not "seriously looking", it helps immensely that you bring material that you are familiar with.
I bring at least three discs:
Diana Krall - Live in Paris
Fiona Apple - Tidal
and now my third one:
NIN - The Fragile (ok, it's 4 discs all together, and it replaced Sonic Youth's "Daydream Nation" )
Be prepared to hear variations. Some speakers may reveal detail in the recording that you didn't hear before (noise, compression, distortion) or (new low notes that never heard before, or the faint sound of chimes being stroked ever so lightly).
And, it could be how they are set up. Even good businesses and companies sometimes have the equipment set up wrong or improperly on accident (on an off day) or on purpose (to get you to buy what will give them a large profit margin). It's hard to tell really. You have to look at everything in consideration.
I auditioned a pair of 606's a while back and something wasn't right at all.
Lo and behold, the wires on one speaker were reversed (making it sound out of phase). Fixed that for them!