Just to let people know that are using the ADD51T. I just picked up the SP13000 Via MB and the Audiobahn ADD51T. I had the same problem with the spdif coax out to the ADD51T. I read through the motherboard manual and found a spdif header on board. This had 3 pins 5V, Gnd, spdif. So I took the optical out connector from an old computer case, cut the connector off and crimped new pins on it. Plugged it in to the motherboard and now I have optical out from my motherboard. No adaptor needed. So before ordering an adaptor check to see if you have the optical header on your motherboard.