I don't know much about the sound control stuff but the wall is 2 x 6 and the enclosure is 2x4. Their is mineral wool behind it to fill the 2". I expect the whole wall will be filled with it and it was probably easier to put that in prior instead of trying to jam it in after. The seams are caulked with fire rated caulk.
I was just asking as "strange" because the recepticals were not attached to the main studs but centered in the middle. H/O said when he has the coin he wants to put in a full control panel to run scenes. It will be large enough for that in the future and still have some sound control. It seems to make sense I guess.
Here's the answer to Rock Wool granted it's from the
Association that make various types of this stuff!
Why would it matter as to where a box is attached, the product you are using is "
Listed"
Article 100. I build bridges all the time, it sends one to other places!!!!
I was frankly looking for the phrase, "of like construction", or like construction to be used, I couldn't find that but found some other "Stuff"!
Addressing the second paragraph:
Frankly there sound proof'n in MO. But if you want to look and something
Atricle 110.15, which you seem to be working with including the 120V.
Article 110.26 leads off or
Article 110.27 which deals with 50V or more and Accidental Contacts, or
Article 110.34(B) which highlights Seperation of Low voltage equipment, but your all really doing that as you've isolated the box what I assume is low voltage and 120v.
Arlington a listing of their Comm. products and others have some great products that are even angled for the modern application of TV, cabling and stereo's.
If the stuffing bother you for some future servicing then I'd
(if at all possible run a conduit to point)install conduit and go to 4 sq boxes, or even 4 11/16 with a 2 gang mud rings.
You can't install all future needs, but you sure can get close by asking the owner what they really need!