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.
Ok, the 2nd part to the screw holding power and rattle
When I examined the resilient I notice that a lot of the screw holes were bent outward making them larger so it wasn't engaging the screw well. This was probably why when I shook one part of the wall another part would rattle, The screw was rubbing the resilient and not holding the board. Cause ... the installer was over torquing the screws. It would not be good if that explosive movie brought the ceiling down on me ... that's a little bit more in the action then I'm going for ...
I did some experiments and this was the case. If I over torqued the screw the resilient could easily be pulled away from the board easily. If I torqued it snug the resilient was on tight.
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'm not sure this is a good idea. I'd want a solid connection where the screw was firmly attached to the channel. If you allowed the screw to move around it might expand its hole or work it's way out.
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.
I am planning OSB as the first layer. My main reason was so I could attach things to the walls like molding/speakers if needed. This is especially true of the ceiling as many speakers will be hung on it.
The room is being built the way it is to be as sound proof as I can make it. My understanding was that the extra board would make the sound proofing better. It was also my understanding that there is little low end sound adoration with two wall boards.
Now you have me questioning that. It would be great if anyone could give me more feedback on this ...
My current plan for the low-end is to drive it with 4 subs to even things out.
