Dedicated power to audio system—how extreme to go?

Inspired by this post on the What's Best forum, I got to thinking about a truly dedicated circuit feeding the outlet where my audio stuff is plugged in. We're going to do some other work that will require a new subpanel and other electrical improvements, so this might be a good occasion to make some improvements. Right now my system feeds off the upstairs subpanel that doesn't have any big appliances on it.

 I've jiggered things around in various ways so that there's nothing else on the #12 AWG circuit feeding the audio system, although there are intermediate outlets between the breaker box and the system. The breaker has a GFI (ground-fault interrupter), and I've read that even these can have a negative sound quality impact. In the linked post people refer to "audiophile" circuit breakers, but I didn't find any for the US market. The room lighting is on a separate circuit. The house was completed in 2005 so everything is pretty modern up-to-code, but I don't know where the utility company's transformer serving us is located.

The post says you should use wire with a 4-mm cross-sectional area for 120-volt service, and according to this calculator, that translates to #6 AWG wire, and of course you'd want to get the cryo-treated, if you can somehow coil it up to get in the cryo-fridge.

But seriously, if anyone has experience with a true breaker-box-to-outlet dedicated electrical service, I'd like to hear about it.

My listening room is a remodel from about 1991. My electrician father in law insisted there is no reason for a separate circuit or line and so the room was initially wired just like yours. Then over the years I have redone it a couple different times including yes rolling the 4 ga wire into a pillow case and having it cryo'd. As a result I know from experience what several different methods actually sound like, how they perform for the money.  

The biggest, best, most obvious and cheapest improvement is simply to replace the standard daisy-chain of outlets with one dedicated line running direct and unbroken from the box to your outlet. This one thing alone will make a difference you will easily hear and for very little cost.  

This works because each connection in the chain is a point of micro-arcing, eddy currents, and RFI entry. It does no good to unplug stuff, the connections themselves are the problem. Remember this for later.

If you can do it with thicker wire so much the better but then you run into problems with electricians and electrical code. For example if you run 4ga that will require a sub panel or some sort of step-down box, and you will just about have to do it anyway simply because that wire is so darn thick. But now remember connections are the problem? So your box just added a whole slew of connections.

If you are going to add connections then make it worth your while. Run 240V to a quality step down transformer located close to your system. This is what I do. This is another big improvement but unlike the first one this one costs real money. 

If you want to go the Full Monty I would skip right past all the crazy expensive stuff and go full battery power. Like everything else this has to be done right. The benefit of batteries is they eliminate all the RFI and EMF riding on the line. In order for this to work however the system must be designed to be disconnected from the grid and running full battery isolation when playing music. It can be connected and charging the rest of the time but must be physically isolated otherwise.  

I have heard the improvement running just one component off batteries. Based on that I would say if you do your whole system that way the results will be jaw-dropping and probably beyond the reach of any other method regardless of cost.

This experimentation of mine, it was all done back in the days before magical fuses and all the incredible advances in power cords, interconnects, speaker cables, isolation platforms like Podiums, and all the rest. Looking at it now there are so many much more beneficial uses for your time and money I would just run the one fat wire and call it good.

The systems that I have heard with battery power lose it when it comes to dynamics. Especially amps.

Nice thought though, but the technology is not there... yet.