I was in the same boat. My av7702 mkii has started having some issues. I was willing to shell out the extra for the avm 70, but it's extremely hard to find and I need something asap. Given the fire at akm, the av7706 was hard to find also, but in stock at a few of vendors while most said it could be weeks or even months before it was back in stock. I considered going the denon route, but read a lot of reviews of comparing them and the totl marantz avrs to the av7705 and 7706 and from all accounts, the av preamp always seem to come out on top, and that's even including the vaulted x8500 denon. Plus sometimes we can get too obsessed with measurements that seem to be inaudible.
So I pulled the trigger on the av7706 from musicdirect. The feature set, balanced outs and being more future proof than the 7705 put it over the top for me. I'm running an atmos 5.2.4 setup and in the process of expanding my setup to 7.2.4. It will be here Friday, so I will post my findings after getting up and running.