Great CDs for auditioning speakers?

[Drew Tronvig]

I'm shopping for speakers--so far the Definitive Tech 7000 series is my
reference standard (I'd also love suggestions for speakers in the
~$2000-a-stereo-set range) and I would welcome suggestions for really
well-recorded natural-sounding CDs to audition speakers.

I would mostly be looking for acoustic content and mostly small groups,
so I can listen to individual instruments and voices. I have eclectic
tastes so almost any good music would be of interest. I am learning
string base so any acoustic or electric/acoustic bass content would be
great. Some other ideas:

Solo or small-group-accompanied piano
String quartets and/or piano-and-string quintets
Chamber groups
Small vocal groups, possibly in audible acoustic spaces,
such as chapels, etc.
Solo cello--a good test of smooth crossover
and phase consistency, I think
Great voices, solo or with small groups, mostly acoustic
String bands, Bluegrass or whatever
Organ, such as Taccota and Fugue, preferably with room sound

I dont think I'm going for surround sound but a couple of Superaudio
CDs would be interesting.

Thanks for any suggestions,
Drew