[shnxx]

There are plenty of threads on this forum with folks who have had similar issues. The fact you now know that the Acer can output HD-Audio means that its most likely a settings issue. With HTPC's, double-checking is usually the best and most successful approach to solving these sorts of issues and even then, check again just to be safe.

Could it be the case that HD-Audio is not supported within windows?

IIRC I think I've seen it mentioned with other (Intel based?) motherboards/systems before. I get the feeling that HD-Audio bitstreaming may work within Linux/openelec but not windows.

shnxx - It could be worth installing openelec on a usb stick (so you won't lose your windows setup), to try as a comparison?

It's a very quick OS to install and setup and will happily boot & run off a usb stick.

At least that way you can know if the hardware supports HD-Audio. Getting it to work in windows may be a different matter.

Windows can definitely support it based on what I've read.
The issue seems to be about the driver on the hardware.

It's a known issue

https://communities.intel.com/thread/522...5&tstart=0