I am surprised by the lack of interest here. This little box sounds pretty good for being a one cable DAC and headphones amp. The sound signature is a little forward on my Sony MDR-V600, but it's good. I plan on trying other cans to match. For $169, you can't beat it.
I think the problem is that it's bumping into the Fiio E17 at that price point, which is also a one-cable USB DAC. The Fiio E17 has even more features like a simple equalizer for bass/mid/treble, ability to pair with iPhone/iPad/iPod Touch via line out through the dock connector, and it's a lot smaller and more portable than the D1.
DjAmTraX, how does the Audioengine D1 sound compared to your MacBook's headphone out when using the Sony MDR-V6? I have the same pair of headphones. My MacBook's 24-bit 96 kHz output sounds just fine. How much better can it get?