My XDA-2 just arrived today and I already have it hooked up! I placed it in my office in place of the PopPulse DAC, just to test it out. I think eventually it will live in the main room.
First impressions are WOW, the device itself is solidly built with a lot of attention to detail. Double boxed, wrapped in a felt cover for shipment. The remote control feels and looks like it's carved from billet.
Hookup was a cinch. I am using USB to the DAC and then from there to the NAD1600/2400 and then the Morel Duets are pushing the air around. Out of the box, the DAC meshed seamlessly with the computer's USB signal. No fiddling necessary (unlike the MusicHall DAC I tried out a few months ago, which had issues talking to the Mac and the AirPort Express).
I personally like the blue display and with 5 dimming modes, it can be tamed depending on ambient light conditions or mood.
The sound is excellent so far. Not sure how I would swing a side-by-side comparison with the PopPulse. But by itself, the Emotiva seems to present materials a little differently. Bass is a bit more controlled, and some studio "artifacts" are more noticeable.
Overall, for $220 SHIPPED to my door, this is a great deal. Everyone should have at least one! (My only wish is that they packaged it with an Apple Airport Express built-in so I could stream directly to it.)