(another variation on) soundproofing party wall

Hi I want to add sound insulation to the party wall in our bedroom (Victorian brick terrace), since the neighbours use theirs as a living room - there's not a huge noise problem, I just want to make sure that their conversation and TV doesn't keep us awake.
I've been reading old posts and I'm having trouble deciding between whether to: 1) add mass to the wall with 50mm battens, 50mm insulation slabs and plasterboard; or 2)build a free-standing stud wall 10-25mm away from existing wall, stuff with rockwool and cover with plasterboard. (If #2 is best, should the rockwool go in the gap between wall & stud-wall, leaving the studs "hollow" ? ; or should the rockwool sit in the studs, leaving the gap empty between the walls ?)
There is another complication though - and do tell me if you think that this will negate any noise reduction: This is the only room in the house with an original cornice, and I am loathe to cover/replace them, so I was think of only putting the battens or stud wall from floor-level to just below the cornice. This would leave the top 50/75mm of wall (with the cornice on) untouched. I would have to cover and seal the gap at the top of the plasterboard. (which, if I go for the stud-wall approach, would effectively join the top of the stud-wall to the existing wall - hmmm ) (I realise that it may look a bit strange too, but eventually there will be some tall wardrobes along most of this wall.)
Given this complication with the cornice, should I go for solution #1 or #2 (or neither/other) ? Cheers - Dan

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