As expected, it shows up as a zone in MC on my primary PC, and it's controllable both from there are from JRemote. So I'm not even going to bother trying to find the configuration file that will allow me to change the default bit depth for the display to 24. If anyone lets me know what it is and where it is, I'll go in and give it a shot - but I run the 'bone headless anyway, so this isn't a problem. In fact, it may have been happening all along - the HDMI output didn't work when I first got it, so I never put it on a display. There were apparently a lot of early problems with the video drivers that have been fixed in recent software updates.
Thanks for the input!!
David