I have a sound proofed room. It's constructed like this:
Specifically, the layers of the wall are:
The exterior of the wall is 2" from the MDF and 2.75" from the studs.
Can I attach things to the studs even though it's 2.75" away? Is the load bearing capacity any different? Can I hang things like heavy cabinets?
Since I have MDF everywhere, can I attach heavy things to the MDF and ignore the studs?
The room is sound proofed by using certain sound resistant materials in a certain manner. One of the key concepts is to isolate the interior wall finish from the exterior (or other side of the wall) wall surface. In this wall, RC-8 resilient channels are used to isolate the interior wallboard from the studs. This keeps the sound waves (or most of the sound waves) from passing through the wall.
If you install hangers, fasteners or blocking through the interior wall surface and attach it to the other surface, you may slightly reduce the quality of the isolation, but not significantly enough to be detected. I would keep the fasteners to a minimum. If you think about it, you're making a "conduit" for the sound to travel through the fastener and into the stud, then through the stud and through the wall material on the other side...exactly the opposite of what the RC-8 channels are doing...isolating the 2 sides of the wall.
You may want to use cabinets that can support themselves so they don't need to "hang" on the wall. Then, just use a sufficient amount of fasteners to keep them from tipping over.
You may destroy the sound barrier effect if you put any fasteners through your current setup. It isn't the approach I would take. You have an extremely expensive walls, make some effort to protect it.
I would build a non destructive hanging setup. You would build two ladders as tall as the room out of at least 2x4 thickness of wood. And pin them to opposing walls by putting a pair of 4x4s across the ceiling. The ladders can be any width, consider the weight of what you are hanging. And be careful not to damage the drywall when making this tight.
Bookshelves should have another vertical support pinned to the wall every 3 foot. They get heavy when full.
Then you would have a hanging system for two walls, and across the ceiling. I don't know if they still do, but college students used to do this in dorm rooms for hanging bunk beds off the ceiling. It took up less space than the free standing bunk beds. If I can find an images of the kits they used, I will post it. They haven't appeared in my searches so far.
