Installing Dedicated Power Lines -- Need Advice

Depending on where you live, the applicable code will indicate whether you need a permit. I chose to use a commercial electrician to do the work, based on positive experience with that electrician doing other work here. @Jea48 is very knowledgeable on code-related issues (nationally, he may defer to the local code and those who know it) but a lot of it is also good practices-- most electricians in my experience are not necessarily specialists in audio and may regard some of what is taken from the chat boards as nonsense; in other cases-- and I found this to be true in the current house, using the commercial electrician-- he was pretty much totally onboard with the various suggestions. I had them install a whole house surge protector on the main service panel, run a feed to a sub panel that delivered 60 amps, which in turn feeds a 10kVA iso transformer that sits in a large weatherproof NEMA case about the size of refrigerator/freezer cut in half. (You can see it on my system page here). The output of that transformer runs from 4 gauge feeder to a sub panel adjacent to my listening room- dedicated lines are pulled from that interior sub panel-- 10 gauge, running to hospital grade Hubbells sourced from Albert Porter (unplated contacts, brass strap, no fancy cover plate, I think they were nylon in bulk).
I had a chance to listen to the system for a while without the iso transformer, which was still in the process of being put together in Michigan, so a junction box was used to connect the two parts of the circuit where the isolation transformer was eventually installed.
My immediate impression was that the system sounded a little bright, but it also had not been fully dialed in; I had moved from NY metro to Texas, new room, new challenges. The system with the iso transformer is quiet, I think the overall infrastructure here is newer and in better condition than that I had in NY (notwithstanding the power outage here recently due to the extreme cold).
My loudspeakers (Avantgarde Duos) are extremely sensitive at 104 db/meter, so you can hear electrical gremlins if there are any anomalies. Inter-component grounding issues, tube noise, etc. are all pretty hard to ignore. My goal was to reduce the overall noise floor to increase the amount of musical information I could hear at low levels. That also meant reducing the amount of ambient noise in the room. I do not like heavily treated rooms which sound "dead" so I used a minimal amount of treatment (bass traps, some multilayer treatment on the front wall window) and a large Persian rug that more than fills the room. The house itself is quite old, made of shiplap that has petrified in the Texas heat and is harder than hell.
I’ve been through a number of dedicated rooms over the years, starting with a brownstone in Brooklyn Heights, then a few houses in the lower Hudson Valley before my move to Texas. Each time I learned something.
I would ask the electrician what he plans-- some don’t necessarily want to work with the heavier gauge wire, may not be as concerned with spacing between the lines (which may also be a code issue, I dunno) and get some input here before he starts. Usually contractors work with the same subs but if you aren’t confident in the electrician that your general contractor wants to use, it’s gonna be on you to find someone better. Frankly, my best experience has consistently been with commercial electricians- they are used to working with heavy duty stuff, whether it is lighting or sound, they seem better equipped than some of the residential electricians I’ve encountered over the years.

Thanks very much Millercarbon for your thoughtful and detailed response.  I now understand I'll have both outlets on one circuit.  One clarification-- does plugging in different components to different outlets on the same circuit create ground loops or just plugging into two different circuits? 

Point taken on plugging the amp into the power conditioner and thanks for the Decware suggestion.  My dealer who sold me the Line Magnetic amp also carries Shindo and is suggesting I get a Shindo Mr. T.  It is, as you suggested, a bit more than twice the price of the Decware.  I will take my time with the conditioner and power cable part of this since I'll be plugging into a really new system with new speakers in the new apartment and want to wait until I'm in the new place before making any decisions.

Since the walls (hopefully) will only be open once, I am considering wiring the whole audio circuit with JPS Power AC In-Wall 10 gauge wire.  

Whart, thanks for your suggestions.  Since we are gutting the entire apartment, permits have been pulled for everything, plus landmarks approval, etc.  Expediting this project has been no small feat! I'm confident our GC will only use a good electrician.  We are in a prewar building in Manhattan, so downside is the same creaky electric infrastructure you had in Brooklyn, but upside is buried cables not particularly susceptible to surge and outages.

A ground loop is nothing more than the current has different paths to ground. This always happens, because even on one circuit there are lots of things plugged in. What you want to avoid is different electrical potentials. As long as they are all the same, or very close to the same, then no problem. 

This is why often times people are able to get away with running off more than one line. You could run a separate dedicated line to every component, each with its own conditioner (or not) and have no problem as long as they all have equal ground potential. Where the hum and noise comes in is when it is different. How different? When will it be a problem? Only way of knowing, do it and find out. So these things are more good housekeeping or good practice than guarantees.  

The one good thing about a dealer is you can bring the thing home and try it. Only problem, I have heard enough of these things to guarantee just about any of them will sound to you like a big improvement. It is only after going to the trouble of comparing a bunch of them that you will be able to figure out if one is better than another for the money. Do that enough times and then you are able to look at something like the Decware and go, yeah totally worth it. But you kind of have to go through it.   

Look at the neverending amplifier thread to see just how endless that kind of thing can be. 

Don't know what the JPS Power wire costs, or what your budget is. But I can tell you this. Look at my system. Read the details. Notice I am not recommending you use cryogenically treated wire, 240V step down, etc, etc. Why is that? Because it doesn't work? 

No. It totally works. But I have learned over the years there are lots of things that are way more bang for your buck. If it was me now (and I was paying electricians and having to follow code like you are) I would use ordinary 10 gauge, Synergistic Orange outlet, and spend the rest on HFT, ECT, PHT, Orange Fuses, Townshend Pods and Podiums, F1, stuff like that.  

The day you stick an Orange Fuse in your amp, or put it on Pods, or put your speakers on Podiums, or put HFT on your speakers, you will know what I'm talking about.

@millercarbon I'm interested in the Decware unit. I agree it will probably be a good value. He says one thing I need help with, though.

Decware: "Some people will wonder how this approach compares to a power re-generator so it pays to know that a power re-generator is a large power amplifier. It simply plays a 50/60 cycle note (sine wave) instead of music. It is, nevertheless, an amplifier whose performance is affected by incoming power quality just like anything else therefor it would make sense to plug a power re-generator in the Zen Line Conditioner."

My understanding was that if one buy a regenerator, they're done. That thing takes whatever power is in the wall and by regenerating power in a clean way, also cleans it up. That's what I take the P.S. Audio products to be claiming. Did I miss something? If one goes the regenerator route, do they also need a conditioner? 

If one goes the regenerator route, do they also need a conditioner?

No, you don't need both. A regenerator takes imperfect AC from the mains and generates the signal into a new clean sine-wave without noise and distortion. It's creating a new AC signal.
Conditioners usually apply filtering to the incoming AC to remove noise and grunge. It then passes this signal through to it's output.