The new room is currently being built (old garage getting converted to livable space). Putting some treatments in the walls (decoupling the drywall from the framing) and working with GIK to add in treatment around the room. It’s still in progress.
You should definitely read Premium Home Theater by Earl Geddes for a good education on optimizing room design for audio. It’s very informative and easy to understand and goes through things like resilient channels, Sheetrock type/thickness, etc. — things everyone should know before building a dedicated room (chapters 5 and 6 in particular).

