Hi Maabb,
Thank you for your question. The proposed scenario is quite complex, and I seem to miss some details to be able to tell if it is gonna all work the way you picture it. Let me put a few comments below.
- Do the HDMI outputs from your processor still output HDMI audio? Does the Marantz work just as a HDMI switch between multiple sources (AppleTV, DIrectTV, etc.) or does it also perform some processing internally? What is the HDMI audio support in terms of sampling frequencies, etc. Most processors downsample all audio to 48kHz for processing.
- For volume control, you don't mention which device the remote belongs to. It depends if either the processor or a downstream TV connected through the VanityPRO is able to send CEC commands for Stand-by and volume.
- How is the room correction done in audyssey pro? I assume it is meant to run in the Marantz. In that case you need to make sure that the processed audio can be passed through via HDMI output and not just internally into the analogue pre output or amps in case of a big AVR.
- In theory it can all work the way you wish, but there are too many variables and unknowns. You could verify the basic functionality with a cheap HDMI stereo audio extractor ($15 on Amazon) to see if the signal chain works, but that won't tell you if the CEC (volume) will work too. Or you can get the VanityPRO straight away as a demo and see if it all works.
Any further questions, don't hesitate to ask here.
Regards,
Pavel