Need setup help - MyTek Manhattan II and Subs

I just received my new MyTek Manhattan II, which I’ll be using as a preamp, DAC, and network streamer for music.

My other components are:
KEF R11s
KEF surrounds for full Atmos
Dual custom Deep Sea Sound Subs
Marantz SR7012 AVR
Parasound A21+

I know the MII has a home theater bypass so I can connect the L/R RCA preouts to the MII and then run XLR out to the Parasound.  The subs are connected to the Marantz via RCA.  This should work for movies.

However, I hadn’t thought about how to integrate the subs when using the MII as a preamp, DAC, and source for streaming music? This has to be possible, right? What am I missing?

Woof, I hope not! I don’t know that I can stomach another $3K so soon after this purchase...

in doing some further research, the Parasound has a “loop out” on the back and the manual says it can be used for powered subwoofers.

My Deep Sea Sound subs use SpeakerPower plate amps that have controls like this:

It has controls for LF Adjust and Crossover crossover point, so could I run the loop out of the Parasound and set the crossover on the subs?

You can give it a try and see what you think. It’s great that it has a "delay" setting (which I take to be a more honest name for the "phase" control on many subs, and which is needed to get best results).
I’ve had best results high passing the mains *and* low-passing the subs, but I’ve had many audiophiles say that was overkill. Still other say they used to think it was overkill, then tried it and won't go back.
From the Mytek, you can run balanced out to your amp and single ended to your sub(s).  Not sure exactly how this works with two subs...maybe you can use some sort of splitter.