Can you provide the below?
1- How you have the HTPC connected? Is it via HDMI, TOSLINK, Analog, etc
2- Are you connected to an AVR or directly to the HDTV
3- You have Intel MEI installed? (See Intel MEI is needed for bitstreaming HD Audio with H55H57 chipsets)
4- What format did you rip the music to? If WMA then you may have an issue with your DRM license. Let me know me and I can provide instructions to reset your DRM cache.