For stringed acoustic, David Grisman, mandolinist, does a careful job on his Acoustic Disc label. "I'm Beginning To See The Light" by Martin Taylor (guitar) - David Grisman Acoustic Jazz Quartet would be a good example. Great playing, and swings... overall a little too tasteful and mainstream to be favorite music for me, but still a great listen, and in terms of showing off your system, the relaxed nature of the music makes it easy to listen for the many nuances of the playing and the sound. ..... How about piano? What do people like as a test of fidelity to the piano's sound, whether solo or not, classical or not?