so you've plugged it in and it doesn't recognize the device as the audio output? That means there's no drivers in the kernel. You'll have to modify the drivers inside the kernel in order to get the device to work.
Honestly, I'd check into the forums over at Hardkernel for the issue. Its very possible that the guys there can tell you exactly what you need to do based on the Vender and product IDs of the DAC.