USA electrical advice

The 20-amp circuit is a good idea. Whether you require 10 or 12-gauge wire depends on the length of wire run from the breaker box. Either way, I'd go with 10 gauge to minimize resistance. Some electricians may steer you toward 12 gauge (if that meets code per length of run) simply because it's easier to work with. Insist on 10 gauge.

The outlets are important IME as they have an audible effect on system sound, as does the power strip. There are some valuable reviews of both power strips and outlets that you may find worthwhile reading. Ultimately, your ears will have to be the judge. I went with a single audiophile outlet and a simple unadorned power strip in my system. Details are in my profile. 

In your case I'd suggest having the electrician run two separate, parallel circuits into duplex outlets and eschew the power strip. Use these for your Naim gear and TT and use existing circuits for your TV and whatever else is in the room.

An alternative option (perfectly viable and one I'd seriously consider in your situation) is to have the electrician also run a dedicated 220-V circuit. From this you can power Naim gear bought directly from the UK. The direct, tariff-free pricing should more than offset the cost of the circuit materials and electrician's wages.

Jered, I would have a discussion with someone like Chris West from AV Options or else somebody like Manu who works with Naim's North American distributor, Plurison. Either should be able to give you the best guidance with regard to what to discuss with your electrician on any proposed US mains installation.

Naim’s advice to me in the UK, so not necessarily the same, was to use a standard T&E (two core + earth) 10 square mm cable if possible. This is quite thick, more like 7 or 8 gauge, and your electrician may be unwilling or unable to fit this into a socket designed for thinner cables. Fitting fat cables into one socket might be OK, but daisy chaining 2 or more sockets means fitting two sets of wire into each one, which gets more difficult. 

You may find it easier to fit a single socket and run a mains block from there. A block with no fancy filters, and with star earthing, is the usual recommendation. Not sure if there’s a US equivalent of a Grahams Hydra?

 I would try to put just the HiFi on the dedicated supply, and put anything else, such as the Mac you mention, an an existing mains circuit, to give some isolation from the cheap, often noisy power supplies these consumer devices often have. 

Naim's guidelines are UK only and should not be considered or applied outside of the UK.  In all cases you need to ensure that, whatever electrical installation you choose, it conforms with electrical code for your country or region.

If you're in a position to get the mains right, also consider a non filtering balanced transformer. In the US Equitec are the gold standard so I have heard.  

They aren't silent so are best used if your breaker box is somewhere like a garage.

I appreciate the input everyone. Looks like I will run two dedicated, separate 20A lines with 10 gauge solid core wire. Fortunately the run from my circuit breaker to the duplexes is fairly simple. Once I get these in place, then I can play around with things.  Chris/Nick are sending two Hubbell duplexes, and their Ultra-HBL power strip. One person recommended doing an ohm test on the ground to ensure is it <5 ohms, so I am exploring this suggestion with my electrician, along with doing some research on the Equitech Balanced Power unit. 

Is the 10 gauge wiring directional? I read a post somewhere on these forums that the correct direction has writing on the wire insulate that reads from panel to duplex. Any truth to this?

Here's my listening room. I'm pretty ****ing excited!

https://imgur.com/gallery/Upznc5D

JeredH posted:

Looks like I will run two dedicated, separate 20A lines with 10 gauge solid core wire.

Excellent decision! I'd say play around with various duplexes and forget the power strip.

Nice looking room. Good luck!

1. Don't be talked into using 12 ga. Pay the nominal extra for 10ga. 
2. Use a power strip instead of multiple duplex sockets. Really. 
3. If you have a dedicated line, make sure the sparky completes it with a dedicated earth composed of at least two long copper ground spikes separated by a couple of meters. and run the fattest wire from the ground rods back to the circuit box. 
4. At your level, a farkin big balanced power transformer is at the same cost bracket as a 555PS-DR and will benefit every single piece of equipment and give dramatic improvements across the board that are probably superior to a single 555PS. Balanced power can objectively allow double digit dB lowering of the noise floor with no downside. 

When I was running active DBLs I had a variety of wall sockets I had installed that allowed me to try with the same gear. 
a) Standard 10A shared line with some other rooms. 
b) Dedicated 20 A line. 
c) Dedicated 30 A line. 
d) Dedicated 100A line!
e) 10 kVA balanced power transformer (search Equitech on the forum). 
f) A half a dozen high quality PS-Audio wall duplexes vs  hardwiring a Wiremold strip into the wall.  The latter was demonstrably better. 
g) A PS-Audio PP300 mains regenerator  (don't use with any Naim power supply...but its a great way to get 45 rpm out of an LP12 by upscaling the mains frequency). 
h) Various high end power cables-interesting, but they are no substitute for fixing the mains at the source-and with multiple cables needed can easily outcost a balanced transformer. Much better to spend way less on the power cables and put the money elsewhere. Also, check with Chris West about the cryo-ed Tibia cables, which is probably as far as you need to go into cable exotica. 

Also, don't be shy about trying some pricey fuses (keeping the same rating of course). Even cryo treating the standard Naim fuses are a decent improvement. 

Naim power supplies are very fast, but this comes at a cost of being very sensitive to incoming power quality. Extra filtration and regulation could make a quieter supply, but one that is also maybe more ponderous too. Fix the problem before it becomes a problem and give them the cleanest, best earthed power feed you can. 

JeredH posted:

Here's my listening room. I'm pretty ****ing excited!

https://imgur.com/gallery/Upznc5D

Looks like a very comfortable room!  Kitty has his/her perch staked out. Chris and Nick will have totally suitable power strips etc. 

I misread this as electoral advice.

20 amp breaker

#10 AWG conductor

20 amp industrial grade receptacle; I use a Hubbell 5362

BBM 

slight update from electrician: the circuit will be wired with 10-3 gauge wire. He is going to demo existing grounding that's located at meter, set bonding bridge, flex down to new ground rod set underground, then dig 6' and set another ground rod bonded together.   I shared the advice from Ron Toolsie about the ground and sparky liked it!  Also I received the ULTRA-HBL strip from Chris and AV today so I have that to play with down the road.  I want to start with direct connection to duplexes when system gets set up.  Can't wait.