Use lots of screws when attaching the drywall to the channel. I used one every 6 inches and still had to add more later for a few random rattles.
If I did channel again in a room with subs I would lay a heavy bead of silicone on the channel before attaching drywall. I cant remember if you are backing the drywall with osb. If you are it will reinforce the stiffness of walls and increase bass variation. Toss up between isolation and performance.
One layer drywall on channel- walls act as large diaphrams. Help lower decay times of lower frequencies due to surface area. Less stc performance. Potential for rattles.
Two layers on channel w/green glue- neutral assembly. Great stc.
One layer with wood backer- extremely stiff wall. Bass decay longer. Potential for reinforced nodes.
Two layers with wood backer- might as well be concrete, but without the stc performance. Not a great use of budget, but people do it.
The transmission loss of the assembly only needs to be higher than the ambient noise in adjacent spaces. So, if there is laundry nearby for example, an stc of 60 or so is plenty. If you are trying to keep the sound IN the room bass energy is the problem. Maybe the MLV will help with this, but I have no experience with it.
If I was to redo a built from scratch room for me, I would stud my walls as normal, insulate with quiet zone, then run comfortboard 80 perpendicular on studs. Then one layer of drywall. Done. Flexible with super high stc, no chance of rattles.
Whatever you do, put a smoke alarm in there connected to the rest of the house detectors. You arent going to hear it otherwise.
