Well, this all looks very expensive.
As some of you know, I took an alternative and far less expensive route. For the rest:
My wife and I bought an 1865 4.5 story brick townhouse in Newburgh, NY. It had been abandoned for 21 years and was extremely distressed.
We restored it and did so to near passive house standards.
My architect - who I was friends with from my Cooper Union days - got his Masters in construction management at Harvard and while there he became friends with an acoustic engineer and scientist who now holds a number of patents. When my architect told him about our restoration project and the dedication of the 390 sq ft attic room to my audio system, he advised us to not cover with drywall the 6” of rockwool in the walls, nor the 14” in the attic, to simply cover it with fire resistant burlap. So we did.
And the sound was superb. I added Moroccan rugs on the floor, and then pictures on the walls (of blown up album covers of course) as needed to brighten up the otherwise very dead, semi-anechoic room.
Cost? $0.00, because I was already insulating the room for thermal reasons anyway.
I would post a picture but I STILL haven’t figured out how to upload a photo on audiogon.