the power on the 15-pin input is a bit of a challenge. perhaps look for a 15-pin dsub to cannibalize and hope that the power pins you need are used. most of these are molded and theyre not really setup for DIY solder jobs. you need pins 1 and 6 for spdif and 15-16 for power
also re: spdif i have an aes>coax laying around which is simple and robust.