Yes, the only caveat is that the downmix will not normally include the LFE as this will require the output levels to be reduced by 10 dB. Instead this will be selected via a code on the remote and a red light will glow on the front panel to alert the user.
Here is what I would like to do with the DX-5.
Send video over HDMI to video processor. (Actually what I would really like to do is split the video output and send one run to the video processor and another run direct to the projector. I assume an outboard HDMI splitter would not cause harm.)
Send decoded audio over HDMI to Meridian HD621. The audio will not be at the highest level as discussed above, but I do not think this is signficant since I will only be using the Sides, Rears, and LFE from this stream.
The HD621 separates and dejitters audio and video and sends the audio via three S/PDIF cables to a Meridian 568.2mm processor. The 568 sends out S/PDIF Sides, Rears, and LFE to outboard DACs and outboard Placette Remote Volume Controls.
Send L/R analog audio to L/R Placette volume control. I do not use a center, so I do not run into any type of mismatch problem across the front using only the L/R from the Ayre.
My L/R are full range and do not need crossovers. They are farther away than my Sides and Rears and do not need delays, thus they do not need to go to the Meridian processor.
My only difficulty is that I would need the L/R analog from the Ayre to be without any downmix from the Sides, Rears, or LFE, but would need the Center channel included. We had discussed this earlier in the thread and you thought it might be something you might do.
I bring up again in case it would be a simple thing to include while you are involved in the programming. It would not matter to me how it was implemented (via remote, dip switch on rear, internal jumper). So please keep this setup in the back of your mind in case it becomes feasible.