I was on a tight budget and did just what you did, rockwool, single 5/8 Type X drywall, solid core doors as spending the extra $2K would have probably kept me from getting approval from the boss to put an HT room in. Most of the time it is no issue - I can't hear the furnace/air handling unit in the basement, and most of the time we use the room, everyone in the house is in the theater. However you can hear the subs upstairs if we have a friends over and put a movie on for the kids downstairs, and you can people walking on the hardwood (or worse my daughter riding a hoverboard above) on those rare occasions where I'm watching something alone.
If you have the budget maybe you can at least put a couple layers of 5/8 drywall strips in between the joists above, then your insulation, and then dual layers of 5/8 drywall on the ceiling and walls with GG. That wouldn't be as good as clips and channel, but it would still be pretty good and only cost you 5/8" of ceiling height.
I understand if you can't do it budget wise, but I'll also add that it's very hard to do after the fact(near impossible short of a total tear down).
7.4.4 Theater Room: JVC-RS500, Silver Ticket AT 2.35:1 142”, Onkyo RZ830, Anthem PVA-7, Panasonic UB420, Apple TV 4K, JBL Studio 530’s, Dual Driver VBSS
3.1 Living Room: Samsung 64” F8500 Plasma, Anthem MRX 300, Dynaudio Audience 52’s, Dynaudio Audience 122C, NHT SubOne, Roku Express (2019)