Hi, chaz I check again and this is what is said on the guru3d website :
"The power supply for the amplifier sections of this soundcard come from
the Molex connector on the soundcard.
Using the Molex to supply these sections provides arguably
cleaner power supply to these very sensitive circuits and helps
with the over-all quality of the sound and operation of the circuitry. "
This is the link :http://www.guru3d.com/article/asus-xonar-essence-stx-review/9