Yeah, but I like Mozart, Beethoven, Vivaldi, & Bach.
I guess I like the "popular" classical pieces like Pachelbel, Handel, Haydn, etc.
You don't think Mozart pieces are intricate enough?
The question in all honesty is, how much live classical do you attend?
If lots, by all means use pieces you are familiar with. Carry at least a few tracks yourself.
My advice for short term listening (as opposed to long term, at home analysis) like your dealer audition, is small group jazz. You don't necessarily have to like the tunes, but the arrangements are simpler and hopefully, you are familiar with what each individual instrument sounds like, so you can focus in, but not lose track of the whole. Perceptually, it's easy for us to focus on something and say wow, you hadn't heard that before, when actually you had, but just was not focused on it previously.
I use something like this
Dave Brubeck album (pick it up super cheap, new or used) when demoing my speakers at DIY events. Simple arrangements that feature individual instruments on each track (with Dave on the piano of course).
The double bass on Here comes McBride is a favorite of mine to demo dipole bass for those who have never heard it. Listen for the pitch and definition with the 802. How quickly do the string plucks decay, can you hear the plucks of the strings themselves, etc.
If you've heard a double bass in person many times, it's easy to recognize these things. Ditto for the sax, piano, drums, etc. Hopefully you've heard them all in person, close up, many times.
Familiarize yourself with them as much as possible on your own system, then do your best to compare to memory.
cheers,
AJ