So I've been mulling this over for months now, and I've changed my mind back and forth several times. I have already gone to the trouble (and it was a LOT of trouble) to put drywall and green glue against the subfloor above my basement room with the thought that this would be enough soundproofing measure to catch the sound coming through a single layer of drywall with recessed lights on my ceiling. I did also use IB-3 clips to decouple the walls from the existing framing. However, after reading more I decided that these two measures were not going to provide enough soundproofing to meet my goals.
So now, at bare minimum, I'm going to use double drywall with green glue on walls and ceiling. What I'm struggling with is how much further soundproofing gain I would see from backer boxes for my recessed lights, and/or IB-1 clips and hat channel on the ceiling. The room is huge (40' x 18'), and I will have 25 - 6" can lights, so the backer box option is a very time consuming, and not terribly cheap one. The clips and channel seem like a relatively simple and cheap option, but it would require me to use old work can lights, which are not as straight forward to install as the new work lights. Plus I'm a little concerned about my projector hanging from this flexible ceiling because I've heard of people having issues with the picture shaking when people walk on the floor above.
Can anyone comment on their experience with double drywall and green glue WITHOUT backer boxes for recessed lighting, OR clips and channel on the ceiling? Is the DD & GG just a waste without one or both of the other measures? One thing I noticed is that the LED lighting (with integrated trim) that I'm planning to use is an airtight design, and I would be using airtight IC cans, so I think that is at least somewhat of an improvement over a non-airtight can and standard trim. However if the new work boxes are nailed to the joists, there is a pretty solid flanking path for sound to travel through. Even still, I finished the basement at my previous house with standard, new work 6" recessed cans and I didn't implement ANY soundproofing measures, and the sound upstairs wasn't awful unless the music was really blasting.
I'm just thinking about how much time and money these extra measures will take and I'm worried that it's not going to be adding much value.