There’s an inherent conflict. We have a user who trusts themselves to select and configure the right equipment for a very specific taste. And that person is unlikely to ask a decorator (who has no idea of the acoustic properties of different coffee table, sofa, rug, drywall treatments) to then weigh in on the “stuff” in the room.
Plus, like who give a shit how a photo looks… if you’re an audiophile, the REW curves / how it sounds to you are all that matter.
I guess my suggestions would be to nail down some factors like Atmos / no Atmos, windows / no windows, people to seat = few vs many, and DSP options such as Dirac ART, Genelecs system, Trinnov, or others. That will help inform some input parameters.
But if I grasp your idea, more a high end listening space and not a home theater, then I’d recommend an acoustic design firm, plus an architect, plus a gen contractor, and work thru the budget splits such as 30k equipment 45k build 10k electrical & lighting and 15k for the designers, architect, permits and furnishings.
On dimensions, I’d suggest a non-box. Something with a wedge shape horizontally or vertically to help with modes.
If you like to read up, there are some good info in Toole’s book and other books on recording studio design.
I pretty much always recommend DSP but i gotta say if you have good speaker placements and mid field and it sounds good to you, then I would only go for a miniDSP if you want to tweak things for that final final accuracy and management of room modes in the non primary seats. Eg for fun and learning.