Hiya Dave. Brian in Corvallis here. Sorry to have been out of touch for so long.
My take on this topic is that you can't listen "critically" to gear with anything less than excellent recordings. Of course too many of those are "audiophile" pap of little musical interest, but there are some excellent recent recordings of excellent music, as well as many classics, that exhibit these criteria:
(1) good separation of instruments and voices in the soundstage, so they're not crowding or interfering with each other
(2) good rendition of the tonal character of acoustic instruments, without electronic distortions, enhancements, or artifacts
(3) excellent dynamics, both macro and micro (no dynamic compression or peak limiting)
(4) the absence of the overlying electronic "haze" that mars so many pop and rock recordings
(5) a sense of spaciousness, with a "halo of presence" around instruments resembling their natural sound, as opposed to unrealistic "pinpoint" imaging.
Not just "minimalist purist acoustic" recordings, but some well-made multitracked studio recordings, may exhibit these qualities.
I'll get back with a more complete list in the next week or so, but here are a few recent favorites that demonstrate most of the above, and I think folks will enjoy because they're great music:
Ali Farka Toure and Toumani Diabate (African kora and guitar duet, with some bass and percussion)
Hector Zazou - Light in the Dark (medieval Irish church songs, in a variety of arrangements)
Burning Sky - Spirits in the Wind (Native American guitar & flute)
Allen Toussaint - Bright Mississippi (traditional New Orleans jazz tribute)
John Zorn - The Gift (surprisingly pretty, mellow jazz from the master of violent skronk)
Jorma Kaukonen - River of Time (his usual tasteful mix of blues, folk, gospel, and oldtime country)
Louis Armstrong & Duke Ellington - The Great Summit (yeah it's from 1963, but it's an alltime favorite)
Kate Wolf - Weaver of Visions (a career retrospective, recorded in MANY studios and concerts, usually quite well)
These recordings have enough subtle detail (and a wonderful spaciousness) to show up the resolution of a good system, AND they're quite enjoyable.
Comments and other recommendations most welcome.
