Dead(?) ASUS ESSENCE STX II

These things have a molex power connector. God knows why they did that. Mine finally quit with being flakey and simply stopped connecting. If there's a fix, no one's posted it anywhere I can find.
That said, I'm shopping for a solution. My system is PC->Yamaha XC-A5000->Anthem MCA 50->NHT.Looking for something to fill the gap the Asus leaves. I'm leaning towards an external box solution. I have USB and optical ports available on the PC. Would a USB->DAC be an improvement over optical SPDIF->Yamaha XC-A5000?Thanks!