That's weird, especially since HDMI multichannel PCM works fine. It sounds like bitstreaming DD and DTS also works fine over HDMI. I'm going to have to try this again with my OPPO Blu-ray tonight, and may even try to slip the BD30 out of the bedroom to try it.

The quote on page 53 of the Onkyo manual ("‘AUX2’ is used only for the digital input from the front panel terminals. When HDMI IN is assigned to ‘AUX2’ in the ‘HDMI Input Setup’ on page 50, the same HDMI IN can be selected.”) doesn't seem to define any limitation on using the HDMI input. It has to be an HDMI input that is already being used for video on AUX2 (the HDMI Input Setup reference), but that's true of any source - audio must follow video's lead in that regard.