2.2 Channel System Processor Suggestions

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.

You don't want to send the audio from the TV to the preamp.  Connect the audio from your playback device(s) directly to your preamp.  If your bluray player has analog (RCA) outputs, connect those to the preamp and send the video to the TV through an HDMI cable.  Make sense?  Not all bluray players will have analog outs, but most higher end ones will.  My Oppo 4K player and my Roku both have RCA outs.

The Martin Logan 1100X subs have a balanced input so it would be kind of silly to use them with unbalanced cables or with their wireless option.

Have you listened with your subs using an RCA or wireless connection?  Unless you have really long runs, I doubt you'd hear a difference.

The closest thing I’ve found, that’s not a pre/pro is the Nad m12. The only problem with that is it doesn’t have balanced outs for the subs

What's driving the requirement that you can only use the balanced connections on your subs?  Do you need to run a long cable?  Have you considered wireless?  I use wireless for two of my subs and it works great.