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.

@dkidknow - I think the biggest limitation may be that you are likely sharing power, or at least ground, with other units. I've never done a room in a coop or multi-unit building but only in single family houses. The dedicated lines give you some assurance that there are no noise inducing appliances on the same circuit as your hi-fi gear, but they all source back to a panel which feeds other equipment and in turn is tied to a common ground. In one house, I could hear certain lights and appliances despite dedicated lines in a listening room on the third floor of the house, at a remove from the noise inducing appliances. 
I was never too concerned about audiophile branded wire for the dedicated runs or even for the receptacles, going with 10 gauge and the Hubbell hospital grade receptacles I mentioned from Albert Porter. 
Your question about addressing problems at the source would lead me to ask how the power to your unit is wired from the building's utility room-- something you are probably not able to change, but an inspection by a qualified electrician may be informative. I also don't know what code permits you to build in (e.g. an isolation transformer) as opposed to a "black box" that connects to the receptacle. The gent I mentioned in an earlier post in this thread, @jea48, has especially deep knowledge of code and best practices.