I am not a fan of M-Audio interfaces; I've had problems with them in the past.
Focusrite 6i6 would be solid if you can find it. I think it's discontinued now and the cheapest unit with S/PDIF is now 8i6. Or you could try to find one of their older Saffire units. I used to have a Saffire Pro 14 which used FireWire, and it had S/PDIF.