New high end processor

So, if you get a prepro you’ll need another box to power your HT speakers, so two boxes right? The Anthem MRX 720 AVR is on sale at Anthem for $2k, and I’m not sure what else the AVM 60 offers but the 720 seems pretty dang good and takes care of your HT processing/amplification in one box. And it leaves you $3k for a nice stereo pre, which you just take the front L/R pre outs from the 720 into the stereo pre and you’re done again with only two boxes, but now you’ve got a superior preamp in the chain for critical 2-channel listening. Switch between HT and stereo with the push of one button, and in 2-channel the Anthem is completely out of the chain. Couldn’t be simpler really (I did this for years before I had a dedicated listening room), and that’s certainly what I’d do if I had your speakers and amps. FWIW, and again best of luck.

How would you rate the importance of 2-channel vs. HT?

Good prepros are obviously pricey, and if HT is super important to you there’s no getting around that. Me? 2-channel is far more important and HT is a fun treat I just want to be good enough for me to enjoy, which doesn’t really require uber-expensive gear in my case. Anyway, if this somewhat describes you I’d buy a decent AVR for processing and powering center, surround, ATMOS speakers and a really good stereo pre that plays nice with your nice front L/R speaks and stereo amp. For example, you can get a Yamaha Aventage RXA1080 for about $700 from Accessories4less.com (or an Anthem AVR if you want to kick it up a notch) and have a bunch left over for a really nice stereo pre like a used JC-2BP or Pass X1 that will likely outperform a $5k prepro for critical stereo listening (not to mention you’ll have a much wider selection of stereo preamps to choose from than good prepros). Just another way to go if you’re more of a 2-channel guy. Best of luck in your search.