In the initial avwizard, the graphics overlay test worked, and so did the music once I'd selected the right card. Afterwards, I see the buttons and such around the orbiter gen, but no audio and just a black box for video.
Checking the logs (and I may not be checking the right ones...), there are some oddities, but no errors - the xine player is cycling, and the 21_LaunchOrbiter.sh.log 'Could not find text object: 670'
I'm not planning to use the core as a display, so I'm just moving on with the install. I'd really like to get a handle on how linuxmce operates (which logs to check, etc) so I'm spending more time debugging than I probably need to.