Not that I've had too much time to test audio systems, as I'm just in the market for one now... but whenever I feel like seeing what my home system can do, here are my choices:
1) Live Phish recordings -- if you have a good quality recording, you can really use it to see what kind of imaging/sound you can get out of a system. Some CD players make them sound muddy. If there is enough separation in the system, you can tweak it to hear all 4 instruments, plus vocals.
2) St. Germain's album "tourist" -- great acid jazz album -- beats, acoustic instruments (trumpets, flutes, etc..) great bass lines. Lot's of definition.
3) Metallica "master of puppets" -- after metallica's original few albums, which were all guitar, and before their later albums which some people say are 'soft', this one has a great mix of rhythm, power, and great instrumentality.
4) Miles Davis "Kind of Blue" (remastered)-- if you don't own this you must get it NOW!! This is the smoothest, softest jazz album in the world, and if your stereo can reproduce Miles' muted trumpet, coltrane's tenor sax with the full dynamic range needed to appreciate the genius behind the music, then you've got a winner.
Brian