Thanks for the response Randy, Sorry I'm late getting back to you. I didn't get any email notiication and didn't check back till now.
When you stated that you'd use two layers of 5/8 over quiet rock you meants in the joist cavities directly affixed to the underside of the subfloor? If not, I'm having difficulty comprehending (or motivating myself) with the idea of putting up 3 layers on the channel.
Any suggestions on how to handle things like ceiling fans? I don't think I've seen this addressed online while I've been researching this. Basically, the impact from the upstairs transfers down and often shakes the glass globes on the fan lights so it would seem I've got challenges with the direct contact with the upstairs joist, as well as possible issues with the existing electrical box being too recessed with the final channel and rock install, and don't forget the air flow possiblities around the box. Hopefully acustical caulking or something similar can stop that.
Thanks,
Scott