Peng are you sure? This was the exact question I was asking their tech department. I was very specific in what I wanted to do. It would be crazy to use my XPA-3 for surrounds. Are you saying that only flagship models will allow me to utilize my XPA-3 for the LCR? They got every question I asked wrong! This is after 20 min. of so-called research on their part. This is all they do day after day and they still can't get a simple question answered correctly. Very sad. Peng if you are right it's going back. Maybe I can cancel the order.
I was 100% sure but if the so called rep told you something different then maybe I was wrong. However, if you read up on the X7200WA and X8500H, they have a custom assign option that allows you to re-purpose any of the unused internal amps except the center (the manual is not clear on the center channel) and no other D&M AVRs have that custom assign option.
Also, in the Audioholics.com preview of the AVR-X8500H, Gene said the following (see highlighted bold red):
https://www.audioholics.com/av-receiver-reviews/denon-avr-x8500h-13.2ch-av-receiver
X8500H also has a "Custom" amp assign setting which allows you to map virtually any speaker binding post to any channel of output. For example, if you're using a 5ch amp to power LCR+Surrounds in the main zone, you can repurpose the unused FL/FR and SL/SR amps in the AVR to power Zone 2/3 speakers (the X6400H only has predefined templates for amp assign).
Again, I was 100% but now down to about 80% after being interrogated (just kidding)
. I don't have the Atmos speakers yet so to get this to 100@, may be
@Drunkpenguin can do us all a favor by trying (just pretend) to assign the FL and FR internal amps to the Atmos channels?
I agree with Drunkpenguin, if you can find a good deal for the X6400H, given what you want to do, it would be a no brainer. That thing is even made in Japan, better build than the X4400H and SR7012 for sure.