hdmi is pin-compatible with dvi. a dvi socket actually CAN carry audio, its just that the dvi standard was never intended to. ati include dvi>hdmi adaptors for their graphics cards which now (on the latest cards) support full 7.1 lossless audio as well as 1080p video, all from the dvi socket on the card. so yes, it actually can be done. but the card needs to support it. im assuming they do this by using the dvi socket's analogue video output pins for audio instead (dvi has separate outputs for analogue and digital video)