You're talking abut the LPCM right? I don't know much about it other than it's an HDMI-specific thing.

Unfortunately I don't have anything capable of decoding the newer DTS and Dolby HD streams. Then again, I don't have any files or content with those tracks.

My Pre-Pro (pre-amp-processor) is 7.1 but maxes out with Dolby Digital EX and the equivalent 6.1 channel DTS. No HDMI on it, so I'm restricted to SPDIF and SPDIF doesn't support the newer HDMI-specific HD stuff either. It's not currently hooked up as I'm still waiting to move on some reno work in the family room (lighting an paint).

I also quite like the ability to tell the Box what your external decoder supports. It's a nice way to let it downmix what you don't support. I do wish you could output to more than one port at once though. Currently if you set it to HDMI I don't think it will continue to output on RCA or SPDIF, does it?