I actually experienced the exact same issue with my Windows 8 install on an ASRock CoreHT 252B Mini PC, which acts as my HTPC. Probably the same or similar as you, I'm outputting both video and audio ...

HKEPC reports that Intel's upcoming G35 (Bearlake G+) IGP chipset will have complete support for both HDMI connections and HDCP. With Vista and high-definition formats such as HD-DVD and Blu-Ray ...

So, my motherboard has this Intel HD Audio header. Is there something I can plug into it? It seems like there should be some kind of breakout device that I can buy that will give me digital audio i/o ...