Isolation Transformer and Subpanel recommendations

For 240V, as an example...

http://www.ebay.ca/itm/FPE-5-KVA-1-Phase-240X480V-120-240-Volt-3R-SE2N5FS-Transformer-NEW-/310425276037?pt=BI_Circuit_Breakers_Transformers&hash=item4846c9ce85

Sola/ Hevi-Duty and Acme are usually the best bets for sheilded like this one. (the dashed line in the schematic)

So the transformer could be mounted in the garage and fed from the main panel relatively easily.

From the new transformer the load feeder could pass through the ceiling across the attic and drop down through the top plate into the wall cavity to the new recessed electrical panel. (Assuming the wall is studs covered with drywall.)

For resale you might want to install the new panel in the laundry room. Your electrician will show you your options to meet NEC code for minimum working clearances.

Example, the electrical panel cannot be mounted above the washer or dryer.

.

.
In case you didn't know.

A 5 Kva xfmr primary FLA @ 240V is 20.8 amps when fully loaded. Per NEC FLA is used for determining wire size to feed the xfmr as well as the breaker.
Min wire size #10 awg, breaker 2 pole 30 amp min.

Secondary, 2 windings wired in parallel (120V), will handle a continuous total connected load of up to 41.67 amps
Minimum size feeder wire to new panel, #6 awg copper.

Have you given any thought to surface mounting the new electrical panel in the garage? Mount on the same common wall as the main electrical panel that faces into the laundry room.
Approx how long would the branch circuits be from the new panel to the audio room? How many branch circuits are you planning to run from the new panel? 2, 3, 4?
.

Thank you very much for all of the information! I could definitely mount the new sub-panel in the garage and then go straight up into the area adjoining the audio room. I currently have a 100 ft run of heavy flex conduit for my dedicated circuit; I had an electrician pull individual 5-9s copper runs for positive, negative and neutral through that new conduit 4 years ago so that part is already decided. There is only 1 dedicated audio system 20-amp circuit in the room. The dedicated circuit feeds a Purepower APS 2000 and distributes power to my entire system.

I currently have a 100 ft run of heavy flex conduit for my dedicated circuit;
09-11-12: Zephyr24069

If you put the new panel in the garage are you saying the new branch circuit/s run, from the new panel, would be 100' or more?

I had an electrician pull individual 5-9s copper runs for positive, negative and neutral through that new conduit 4 years ago so that part is already decided.

"5-9s copper runs for positive, negative and neutral through that new conduit" ??? 5-9s??
2) 120V circuits + 1) equipment ground?

Not sure what you mean..... More detailed info please.

There is only 1 dedicated audio system 20-amp circuit in the room. The dedicated circuit feeds a Purepower APS 2000 and distributes power to my entire system.

What is the end result you are aiming for from the new xfmr and new panel?
.

End result is better quality power to my system; the dedicated circuit, rebalancing the house panel to make the dedicated circuit the first one off the main, all other high current circuits on the other leg/phase of the house panel, good quality wiring from the main panel to the room, cryo'ed Oyaide R1 outlets, etc... has taken me a certain amount of the distance but I'd like to separate from the house panel totally and improve the quality of power to the room even further.

individual copper runs pulled means individual insulated strands pulled through the flex conduit for positive, negative and neutral (ground)...

The run to the audio room would still need to be 100' as moving the panel to the garage would be a minimal change as the laundry room where the house panel is today is right next door to the garage; I might be able to save 10' or so but the difference is small by moving the panel. (The electrical main to the house itself is also right outside the garage and only about 20-25 feet from the existing house panel location.

Do you have your system posted? I'd like to see/know what you have going for power as you clearly have alot of experience in this area.

Thanks!