When I introduce a new piece of equipment into my systems, I invariably use familiar cuts of music to see what changes, if any, it makes. Here are a some of the test cuts I use:
Dave Brubeck's Take Five. I listen to the tone and soundstage placement of the alto sax and acoustic bass, and most of all the drum solo, which shows a lot of depth into the left-hand corner, as well as terrifc slam when played at higher volumes.
Fleetwood Mac's Dreams. I listen to the first crashing cymbal, hoping it will be very prominent and crystalline.
Oleta Adams' Get There, which I listen to for female voice.
James Taylor's Mexico and Eric Clapton's Old Love for male voice.
Ray Brown's Starbucks Blues. Ray's opening bass solo reaches very deep and even at moderate volume levels can shake things in a room.
Dave Grusin's Theme from St. Elsewhere. I believe it is an all electronic piece, and includes much that is revealing, especially a passage that has a distinctive pumping bass, as well as one with a vibrating sound (don't know what) that is less distinct with less revealing equipment.
There are many others I use (albeit no classical music), but I've started this thread to share what I use and to see what others on this circle use for testing new gear and what they look for.
Addendum May 24/12: Marius suggests we add cuts we definitely don't use as part of our test cuts. If you have any of these please feel free to add them to your list, and tell us why they are not used.
Dave