Getting the most out of LS50w

I just picked up a pair of LS50w's for my secondary, and much smaller, bedroom setup.  I am powering them with my Furman 15PFi and connected my JL F110 via subwoofer out.  Sound is great.  I had a quick question about getting the most out of them though.  I would like to be able to hook up a Bluesound Node 2i to them via RCA so I can get MQA at full resolution, since MQA is one of the few things they lack.  I'd also like to be able to use them with my LG OLED55C9 and have a full surround system with a dedicated subwoofer channel (since the LS50w's don't have a separate channel and just crossover to the sub) so was gonna get a cheap processor (thinking something alone the lines or Marantz NR1509) which I'd then connect some Q50a speakers in the rear to and the F110 to.  I'd then also need to connect the LS50w's via RCA.  I have a couple of issues though with these ideas:

1. There are only one set of RCA's on LS50w's.  A simple alternative would be to connect the Bluesound Node 2i to the Marantz but I am thinking this will probably defeat the purpose since the Marantz would ruin any gains in sound quality.  My solution was to pick up something like a ARC SP16 (going with a unit with built in phono would later allow me to add in a turntable if I wanted to) or some other similarly good line stage/preamp.  I'd then hook the Marantz and Bluesound both up to it.  Of course this makes the signal chain pretty long (C9->Marantz->Arc->LS50w) but at least seemed like a viable alternative. I wasn't sure if there were any other better suggestions though.

2. The much larger problem has to do with the JL sub.  I can connect the Marantz to the subwoofer with a RCA to XLR cable (ie AQ Golden Gate) and then connect the LS50w's to the JL via RCA's (again Golden Gate).  However my issue is that I'd need the LS50w's to not send a signal if I am using the Marantz.  Does anyone know how I can make this work so that the sub will listen to the Marantz if it sends a signal and not the LS50w's and then otherwise listen to the LS50w's if the source is not the Marantz?  In my main system I solved the problem by picking up a JL CR-1 which allows me to use a Arc SP17 for stereo and SR6013 for HT due to the HT bypass.  I'm not sure how to solve the similar problem with the LS50w's.

I figure to control everything I could always just pick up a Logitech Harmony Elite, which has a phone app so I could control everything via my phone.  Thoughts and suggestions would be greatly appreciated on what others are doing to get the most out of the LS50w's in terms of both sound quality and being able to use them for surround sound in theater setup.  Thanks!