blgentry, I'm positive my pre-pro will accept and correctly decode a 5.1 signal. It works well with my Blu-Ray player, also connected via HDMI.
Ok, good.
What is a "mini-display to HDMI" cable? My Mac Mini has only HDMI, USB and Thunderbolt connectors.
Mini display port and Thunderbolt use the same type of connector. It's used on monitors that have that kind of input. It's a different display connector standard. On Macs that don't have an HDMI port (like Macbook Pro laptops), you can plug in an adapter that goes from mini display port to HDMI and then use an HDMI display. This is the same as the Thunderbolt port on these systems.
I would expect that the "real" HDMI port on a Mac mini would transmit multi-channel audio, just the same as the mini display port.... but I'm not sure. Again, something I haven't tried.
The other part of this equation is how you are sending multi-channel audio. If you're sending DD or DTS audio from DVD, are you bitstreaming it? Or are you letting MC decode it? If MC is decoding it, it will be trying to send multi-channel PCM audio. DD and DTS, on the other hand, "pack" that audio into a compressed stream that's carried in a different way...
It might be worth turning on bitstreaming to see if that works. I'm not trying to complicate the issue here... there are just a lot of variables.
What messages do you get from MC, your pre-pro, etc? Does it "think" it's playing but it doesn't?
Brian.