Music to test with:

Having been to many concerts in different theaters or concert halls from the US to western Europe I have to say that each hall has sounded different. Each time the viola has sounded like a viola but it never sounded the same as in the last hall. Does that mean they used a different viola or was it run through a series of black boxes that caused the sound to change? To say that unamplified flutes are they only music by which to judge the quality of a piece of equipment is ludacrous. What do you know about the acoustics of the setting? Something you might think is the problem of the equipment might just as easily be an acoustic characteristic of the concert hall.
I again ask the question; what is the point of using music with which you are not familiar to test something.
I'm not suggesting ssing2 is wrong, for him/her that might be the perfect piece of music. I'm sure you are not suggesting that fans of heavy metal or techno pop have no place in hi-end audio.
I am looking for suggestions to add to my collection to help in the auditioning process. I did not think I would have to defend my preferences of a broad spectum of music.

In addition to the common James Taylor-type recordings, these are some of my other favorite "demo" discs:

City of Angels - Soundrack
I am Sam - Soundtrack
Ben Folds - Rockin' the Suburbs
Thomas Dolby - Alien ate my Buick
Dire Straits - Brothers in Arms XRCD2
Grateful Dead - Dicks Picks 17
Ray Brown - Soular Energy
Dave's True Story - Sex without Bodies
Apollo 13 Soundtrack (track 20)
The Firm Soundtrack

(I know, a lot of soundtracks, but I like that they have various artists on a single disc and usually offer a consistant recording quality across the disc.)

Unsound, thank you for clarifying the point I was trying to make. To be sure, the sound of a viola will be affected by the environment in which it is played. But if one listens to many violas played in many environments, one will come to learn the characteristic sound of the instrument. The environment may contribute some color, reverb, etc. to the sound of the viola but it won't change the fundamental character.

On the other hand, no one but the artist will EVER know, no matter how many listenings or how many environments, what the the sound coming out of the electric guitar-cum-black box was intended to sound like. Therefore, while it will be entirely possible for one to choose a system that produces a synth sound that one likes, it will be impossible by definition for one to choose a system that replicates with certainty the artist's intention.

Of course one should use recordings with which one is familiar, be they by the Chicago Symphony or by the thrash metal band du jour.

will

Pianorecordings, best one with a Steinway, the other a Boesendorfer or a Bechstein, Soprano arias, string quartets, a brass octet, a chorus, massed strings, or a nice slice of Berlioz' Requiem played at full tilt boogie are the acid tests I use to let a dealers face turn from chubby red to slightly pale. (-;
P.S. That is, if the dealer knows the sound of classical music. A rare breed indeed and an endangered species, but not yet entirely extinct. Cheers,