Does the USB port only function as a stereo audio device for the PC, or can it pass encoded DD/DTS from DVD player software on the PC?

Some USB audio devices on the market can do this, so I'm wondering how it was implemented on the 990.

It's useful for some folks if it's just stereo, but it would be a very slick way to handle HTPC audio if it does support passing encoded DD/DTS from the USB interface straight into the surround decoder engine.