I have a Noren Acoustilock x-cab -- it's a rack enclosure that holds 6U, 37" deep internal. It weighs 206 lb, cost about $2k.
http://www.norenproducts.com/Acoustilock/xCAB.html
I haven't used it yet -- I did try putting a blasting boombox in there and it made a pretty big difference - that's one of the stunts they do at trade shows I was told.
For context, here's what I'm using for the AC power to the room:
http://exactpower.com/ep15a.html
The room has its own 80 amp subpanel, technical grounding, IGR receptacles, and $2k worth of outboard power conditioning to boot. I've tried to get things quiet electrically, and didn't want fan noise that I could avoid. Machine room was out. And I do acoustic music, so gain can be up there. I'll know in a few months if I've got a large paperweight or it actually was worth it.
cheers,
mark