Yes, this is a limitation of the Vista inbox HD Audio Class driver, for HDMI device, the only format supported is 2 channel, 16 bits, 48khz PCM. From: wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of T C Sent: Monday, July 07, 2008 6:59 AM To: wdmaudiodev@xxxxxxxxxxxxx Subject: [wdmaudiodev] HDMI Audio device w/ MSFT inbox driver Dear All, Recently, we found HDMI Audio device w/ MSFT inbox driver is only support PCM 2ch output. Besides that, compressed audio format such as "Dolby Digital" or "DTS" etc cannot be supported even they're checked in "Supported Format" tab. Is this a limitation of MSFT inbox driver? Inbox driver + "Dolby Digital" or "DTS" seems works well w/ S/PDIF audio device. Regards, Cyndi