I will be using a nanoAVR DL which is a minidsp w/ Dirac Live built in with my 975. It will be placed between the sources and the 975. It requires a LPCM signal, and therefore will be outputting full 7.1 multichannel.

If i have the 975 setup for just 5.1, will it matrix the rear surround channels into the sides for me? Or is that rear channel content lost?

Thanks for your help!

I can't say for certain as I've never tested it, but I believe it would re-matrix (is that a word?) it as appropriate.

Yes, the Model 975 will matrix the surround back content, to the surround sides, so it is not lost. Don't forget to ensure your players are set to output LPCM to the nanoAVR DL.

I know nothing of the technical aspects of down mixing but can say without doubt the M-975 does a better job than anything else I have tried. I currently run a 3.1 set up and have tried down mixing through an OPPO BDP-103, an Emotiva theater Pre/Pro (costing four times the price of the Outlaw), an older Rotel, And one of the newer Pioneer units (less than two years of age).

The M-975 beat them all quite easily.