Isolation of HT room

My Ht room has 4 walls that are 6" thick. I know I need to add another layer of drywall spaced a couple of inches from the cement wall with insulation in between to add to isolation. Ive listed below different ways to do it and I wanna know which one should I use. 1) 2X4 framed not touching the cement wall spaced 1" from the cement wall. Top plate screwed to ceiling joist and lower plate nailed to cement floor. Fill cavities with rigid fiberglass or rockwool then cover with drywall. 2) Same as above but instead of 2x4 I use 2X2 so it wont eat up too much of my side walls. 3) Option 1 but cavities not filled fully with insulation. Rigid fiberglass or rockwool is spaced 1" from cement wall then wood studs then drywall.

There are climatic conditions that may change what you should do; if you had followed the first topic in this forum, you would already have edited your profile to include a location, as well as a few other details - please do that now, so we can help you make better decisions - thanks... Steve

Sorry my bad...already edited my profile.

Thanks; now, if you could go thru that first "don't even THINK..." thread and cover as many of the bold points as can possibly apply to your situation, we can probably get more of an idea of what to suggest - also, what's your average humidity/temperature there and will your HT be air conditioned? Steve