Advice- wiring for dedicated sound room

This is what I did in my audio room:
220 Volt 30 Amp from electrical panel to Mud room (adjacent to Audioroom) using 6 AWG stranded copper wire. This is connected to a toroidal transformer which converts 220Volts to 110 Volts at 60 Amps. Both poles are live +55 volts and –55 volts (out of phase). This goes to a sub panel with four separate circuits. The circuits are dedicated and have independent EMI/RFI filtration. This is an industrial product which I got from a company I previously worked for. It was used in medical devices to insure low EMI/RFI. Each of these circuits is run to true ground independently. Then I used 10 AWG stranded copper to the outlets. The circuits are dedicated, one is for the amplifiers, one is for the projection TV, one is for digital source components (all of which have additional independent EMI/RFI filtration), one is for analog source components. Independent grounds are used for each circuit. There have been cautions against this, due to the possibility of having slightly different potentials with 2 grounds. So although this worked well for me, I don't necessarily recommend it. The part that is really critical is the toroidal transformer with two live poles out of phase. I think this made the largest difference in terms of lowering the noise floor. Sean has some good suggestions, which I may add to my system, such as the Pass & Seamor outlets. I'm currently using Hubble hospital grade.

The transformer I used was designed to run in this balanced mode. Again, it was designed for medical equipment, so noise and balanced topology are really what is needed. It's also designed way beyond it's rating of 30 amps at 220 volts. I did do a search with Allied electronics and found several toroidal transformers which should work the same way. Keep in mind this balanced design is not really that big of a deal. The 220V circuits are balanced topology with two poles at 110V. All the transformer is doing is stepping down both of those poles to 55V at double the amperage (minus the loss in the torodial coils).

Mine cost me about $500 plus I supplied the transformer and EMI/RFI filters. I was having other work done, so it was relatively inexpensive. Also, the distance from my incoming power to the audioroom is only about 25 feet. I don't recall the prices of the transformers, but if you go to the Allied website there are several that should work, depending on your power requirements.

Sqjudge: Yes the ground is center tapped. I had to go back to the wiring diagram to figure that one out, but that is how it's done.