I personally use an M-Audio Profire 610, but I always recommend Focusrite products to people. In your case, I'd recommend a Focusrite Scarlett 6i6 (USB, SPDIF in/out). It can be had for around $250 USD. Focusrite makes great products, the only reason I am using an M-Audio is because I bought it a long time ago and refuse to buy another interface, hah. Anyway, check out the Scarlett 6i6 here; http://us.focusrite.com/usb-audio-interfaces/scarlett-6i6