Building a house

All super helpful comments here. I'm in the final design phase for my 17 X 23 with peaked ceiling bonus room over the garage and need to specify build specs for floor, interior/exterior walls, and ceiling. Here is what I am thinking:

• 5/8" drywall screwed and green glued over studs (2X6 exterior and 2X4 interior) with mass loaded vinyl sheets and rockwool sound batts within the cavities of interior walls (regular insulation on the exterior walls).
• 5/8" Quiet Rock on the front wall behind the speakers to create dead end/live end arrangement.

Not sure what to do with the floor joists and flooring could use some help here since this will be the most problamatic surface--brace the joists and add a layer of mass loaded vinyl beneath the plywood flooring? The floor cavities will be filled with regular insulation since the unheated garage is below.

The goal is less about sound insulation and more about making the room sound good--reducing wall and floor shudder, etc.

Thanks!

I agree that you need to think about sockets and wiring in principle. From experience I can say that it is very difficult and expensive to redo something.

@dodgealum  Just saw your post. Hope this is not too late.

I did an old world solution for my home theatre: sand. I put mixed fine and coarse sand into the spaces between joists, about 2".

That is: at the framing stage, double or triple all joists - I used LVL, screwed and glued. Screw and glue (elastomeric M1 works well) a layer of plywood to the bottom of the joists. Fill the cavities with 2-4" of mixed sand. Get an engineer to sanction this.

What you have is a preloaded floor, immune from squeaking and fairly soundproof. I guess you could add rock wool insulation above the sand for the last added iota of sound proofing.

Worked for me. YMMV.

I stumbled upon this thread and thought I'd share my thoughts. I love the idea of a dedicated listening room, and your plan for the walls sounds great. For the floor, have you consider adding an additional layer of plywood with Green Glue sandwiched between them? That should help with any potential shudder.
On a side note, I'm also looking to upgrade my bonus room, and I'm thinking of adding some French doors for more natural light. I discovered doorsdirect2u.co.uk and was wondering if anyone has used them before and what their experience was like. Any feedback would be appreciated!