Dan, my suggestion for a test disc would be Mehta's
The Planets . Excellent sound quality and music with a very wide range of dynamics and frequencies.
Also, your comments above re the DAC emphasize that you have to be careful about matching sound levels as best as you can. "Soundstage and detail" has nothing to do with the DAC process as such, but indicates a volume difference somewhere in the electronic path. Use pink noise and both an SPL meter and just your ears to adjust for difference in sensitivity. The speakers should be placed identically, but next best is to set up the speakers in AB-AB order.
