A dedicated IG circuit in a residance is a complete waste of money. You are running NM to a plastic box mounted on a wooden framing member. This makes it an IG circuit already. The only time an IG circuit would be used is if the circuit were ran in a metalic raceway fastened to concrete or structural building steel. Just run a dedicated circuit to get the same benefit.
The best setup for a basement recording studio would be to run a dedicated 240 volt 30 amp circuit to a balanced power transformer with built in distribution. There are several out on the market. Best ones are made by Equi-Tech (
http://www.equitech.com/). They will eliminate any ground loop problems on unbalanced audio lines, and have filters built in.
