That's my issue, not wanting to tear into the soundproof shell to install a sub panel, run new wire, and outlets. I can plug an isolation transformer into the 240v and get 50amps @ 120v available through multiple 20a and 15a sockets. I suspect that will be enough at realistic volumes & not test tones. But with a drywall crew already going to be onsite for soffit work, now would be the best time to do a sub panel if I was going to do it. I wish I could plug everything in and try it, but that's not really an option.
When you guys say isolated, is a sub panel considered isolated if it is dedicated to the theater, or did you do something special to isolate it like the Torus, Equitech, or RichardGray products? Does it matter if the sub panel is fed from one of the main house breaker boxes, or it should be fed from the outside service box?