Replacement for Marantz AV8801: another prepro or receiver?


My 2014-vintage Marantz AV8801 prepro lost its HDMI audio -- was able to get it back (posted that elsewhere) but likely temporarily. 

Given that I'm planning an Atmos surround system, it's time for an upgrade, which is a shame because it's a great unit, but barely going for anything online and I wouldn't be comfortable in selling it or even donating it to Goodwill. So while it works, I'll try to figure out what to replace it with.

I currently only have a 3.0 system: I currently use the AV8801 to drive two B&W Nautilus 801s for the fronts via a recently acquired Parasound A21+ and a B&W HTM71S2 center with an old Nakamichi PA-7. Since I'm going to Atmos, the conundrum is whether to get another preprocessor: most likely an AV7706, which I'm assured has better processing and sound than the 8801; the 8805 doesn't support the latest standards without an upgrade that is not available and there's no 8806 on the horizon.

The alternative is a receiver like the Marantz SR8015 or Denon AVR-X6700H. All three came out within the last 6 months so they should support the latest standards.  I like the idea of 11 channels of amplification to deploy as I see fit.  If I go that way, I'd like to biamp the HTM71S2 center with two of the channels and use the rest for surrounds (exact configuration still to be determined). 

What I'm wondering is whether the amplification in these receivers is good enough for the surrounds, or whether I should just get the preprocessor and some configurable amplification like Emotiva with a high-power module for the center and lower-power modules for the ceilings and surrounds.  

Opinions?
128x128invaderzim
I would say, start with an Anthem MRX 720 or similar. If it needs more juice, you can always add any number of amp channels.
Interesting!  I'll check it out. I was interested in the HEOS that Marantz and Denon include, but DTS PlayFi looks similar.  The only other thing I see missing is the 8K passthrough support for future-proofing and analog video inputs for a VCR -- I use the AV8801 to convert analog video to HDMI for capture and it's really pretty good at that.  Apparently the Denon and Marantz products above can do that as well.
I agree AVSForum will provide you with access to a lot more information and expertise, but I'll chime in with saying I recommend the Denon receivers or Marantz processors, unless you are going to look at something higher end in which case I'd recommend Trinnov.

Whether or not the Denon receiver would have enough power for your speakers would depend on their distance from your listening position and the volume you watch content at. Personally I have not gone back to a receiver since moving to a separate processor and amplifiers.
Thanks!  I'm leaning towards the Marantz AV7706 processor and deal with the amplification later. I'll post in AVSForum.