HDMI audio not working on 10.10 x86_64 260.19.29
I'm detaching this from another which is focused on video issues, because I don't believe mine is video-related.
My i7-950 machine (Intel X58M motherboard) dual-boots either Windows7 or Ubuntu 10.10 and under Windows7, there is sufficient configuration within the nVidia tool to allow proper selection between many digital audio modes (and speakers if you care). Thus, proper 5.1 digital audio travels alongside the 1080p video on the HDMI cable and works great through my Sony receiver to my Sharp Aquos TV.
However, under 10.10, the video works fine but there is no audio. The configuration tool in System->Preferences->Sound is much more limited -- it apparently recognizes there is digital audio connected via HDMI, but it thinks it is only "stereo" and there is no actual output. Moreover, the nVidia-settings tool only appears to be interested in the video setup for the X-server, and does not address the audio configuration.
I presume the ALSA configuration can be modified to know about the audio capabilities of the GT240 via HDMI, but I have no idea where to start.