The theater location provided acoustical and soundproofing challenges. It is located below the kitchen and utility room. Eighteen years ago when I remodeled our house I should have installed an acoustical break below the tile. Unfortunately, we did not know better at the time. Every footstep, sliding chair or washer/dryer load resonates through the floor joists.
The original design was to have three openings into the theater. We modified the design to allow only one doorway.
Another challenge was getting Dave the carpenter and my partner in this project up to speed on building an acoustical space. Dave builds “Cathedrals” (buildings that last forever) and has never built acoustical spaces. Our running joke throughout the build was, “no matter what size the piece, he would put five screws in it”.
Dick, the water softener man, relocates the ice maker line and Larry, the heat & A/C man, moves some water lines.:

Water lines moved and new acoustically lined duct work installed.:

Lined duct into the theater space and framing started.:

2'"X 6" staggered stud wall to form hallway.:

I insulated the water pipes throughout the theater area. Overkill, I know, but you will see a lot of that

.:

Wall ready for drywall and insulation.:

Roxul mineral fiber insulation started.:

Neat and easy to work with. Notice I sprayed the rim joist with foam to seal and insulate them. More overkill.:

Cut it with a bread knife.:

More later.