OK, I've got a Randall Iso-Cab (well, two actually) but it's not quiet enough for me in the room. I want to build a 'soundproof' (I know that's not possible, but that's the best description I can think of) closet or cab to put the Iso-cab in. I'm just trying to reduce the noise level of sound leaking out as much as possible, but I don't want to screw up the internal acoustics of the cab. How much do you think I need to worry about things like standing waves, or the cab being able to 'breathe'?