OK, now if you can explain what construction you plan to end up with between the iso and the control room - it sounded to me like you intend to panel both sides of the existing frame, and then build ANOTHER frame on the iso side and panel that? I"m hoping that's NOT what you meant, but without some kind of drawing it's hard to be sure. I've done tech writing for a living, and I still sometimes don't make myself clear until the third or fourth attempt.
If your existing wall frame between iso and CR is solidly connected to both floor and ceiling joists, you will have flanking noise at least on the side that has no RC - the sound will excite the panels, they will excite the frame, and the frame will excite the rest of the framing that's rigidly coupled. That will eventually pass through to paneling in other rooms and re-radiate as sound.
Short of removing and re-doing the existing frame between Iso and CR, you could put a second frame close to the existing one, and NOT mount it hard to both floor and ceiling joists - the problem here is that I don't know of a way to do this fast or easy. I've saved myself a fair amount of grief over the years by remembering the saying, "Fast, Good, Cheap - Pick ANY TWO - you can NEVER have all THREE - "
One way you might be able to do it - bite the bullet and BUY sway brackets. Kinetics has them for somewhere between $25 and $50 each - your wall would need them probably every 4 feet. If you're interested, here's a link -
http://www.kineticsnoise.com/architectu ... ation.html
The KWSB might work for mounting a second frame - just remember that each frame can only have ONE side paneled, or you LOSE isolation.
Kinetics doesn't sell direct, so you would need to contact them from their site and get the # of their closest rep if you want to do this.
I have another DIY way that may work for you, but I'm past bedtime and not finished drawing - I'll try to get it for you by tomorrow nite if possible... Steve