Soundproofing a ceiling in a Duplex.
My duplex is from 1915.....which means soundproofing between units were non existent. I live on the top unit and already added a 3mm underlayment and 15mm LVP...it helped muffle the sound (prior to this, I could almost hear conversations downstairs clearly, now its sounds more like adult voices from Charlie Brown cartoons). Well my tenant is moving out and I want to add soundproofing to the ceiling. I know the proper way would be to remove the current ceiling, add special joists and insulation etc, but I don't have the time or money to do that (got a rough quote of $80k for 1000sq/ft...no thanks). I realize I will NOT get 100% soundproofing, but will be happy if I can dampen another 40-60%. I would be STOKED. Since this process cannot be a cost effective trial and error, I hope to get this right the first time.
Right now I am leaning toward Green Glue and another layer of drywall over the existing but wondering if anyone else has had a good experience with another method. Thanks!