One setup I’ve always fantasized about and might be an option in this case….

M5Hp with dual ep500 or ep600 as the stands for the m5s. Select 500 for lower tweeter height or 600 for higher tweeter height.m relative to your MLP ear height. Apply some manufactured or homegrown decoupling to the bottom of m5 and against floor at base of the subs too, as mojo described above and voila. Crossover the m5 to the subs and relieve the m5 of low frequency duty reducing distortion and improving godly holographics.

Why have wooden boxes that could resonate when you could have stereo subs the bring true offerings to the sanctuary. Baptize those hosannas!

This would of course be in addition to your Rythmik subs. Apply proper dynamic high wattage overhead amplification and you’re set.

This setup alone could open a singularity. Use the volume knob to adjust the aperture size. If you’re not careful it may swallow your whole house. Like pulling your lip up over your head and swallowing an event horizon.

All kidding aside, it would kind of like be like having a 4 way speaker that is tuneable. I’m sure this idea is fraught with problems or acoustic malcontents perhaps.

Another thought in line with Hambrabi, I agree with thinking of open space as one volume of cubic space. I think that is good advice. Play with room acoustics and basic treatments. As I’ve been learning in my large open space, adding mass to the space helps and soft cushy things helps too such as thick carpets and underlay, cushions couches furniture etc. The room can always be improved.

Cool theatre plan and thoughts you have. Looking forward to seeing what you do end up going with.