If you're going to do straight two channel you'd be better off with a high quality two channel pre-amp. If it has at least two sets of outs you can run your mains off one set and the two subs off the other set. Connect video directly from your movie source(s) (disc player, Roku, etc.) to your tv or projector and use the analog audio outs to the pre-amp.
You won't have all the room correction stuff, but you probably won't miss it with only two channels, especially if you add a couple more subs. You'll be sending the 4K signal directly to your display device instead of routing it through something else.
If you insist on having a home theater device in the mix, get a preamp with home theater bypass so you don't have the home theater processor degrading sound when you're using the system for music.