My two cents. Much of what is advocated (large diameter wire, solid copper, etc) is technically **true** but of almost zero incremental value, or, in other cases, "a given" whit US and EU code at least.
I do have a 20A home run from my main panel to a single, quad outlet in my music room. I do have hospital grade outlets in it (a big $30 or so). It is 12 gauge (but code demands it anyway!). It is copper (but any quality romex or BX is copper). yes you want it off the phase, but why would anyone create a 20A single phase circuit from two? Mysteries abound.
I do advocate a noise filter of some form, a very large isolation transformer or a low pass filter that essentially removes noise.
Most of these are fairly minor improvements, more a "lack of issues". yes your amp will have a boig power supply and remove much noise. But the lower the starting point the lower the ending point - all power supplies are filters that can be characterized in dB loss at a given frequency - low in, lower out. Iso transformers are a trade off - great in theory, but you need to over spec them (i'd say 2 kW) and some general mechanical noise.
This is not about moving more current. That comes from your power supply, either C or LC. And the current you can move through 14 guage (even 16!) is HUGE relative to what you need. Code covers the limits already. Honestly, crap outlets (bad connections) re among the worst problems, along with old, creaky wiring both in and outside your house. Most modern subdivisions are fine. My public wiring is >70 years old (but meh, still basically fine).
The other BIG DEAL is avoiding ground potential differences (loops). Every single piece of your rig ought to go back to the SAME feed. Use really good power strips if, like me, you have a dozen plugs. Minimize the "spanning tree". Put digital stuff (computers, TVs...) on a different circuit, hopefully ont he other side of a power filter. They represent the noise you are worried about and may have, like spies, infiltrated your room directly - dont look too far, the noise is right in front of you.
Use common sense.
12/2 NM Copper Wire. Available at any DIY store. All you will ever need to meet code and run 20 Amps. Go to 10/2 if it makes you feel good, even though there is probably zero benefit. You system can only draw so much current and the 12/2 wire has no problem providing more than that. All this talk about about exotic cables, or going to 8 gague is just noise, and isn't that exactly what you are trying to get rid of? Would you pay for an 800 HP engine in your car if the local speed limit never exceeded 30 MPH? Than why would you pay for cable that you will never benefit from. Maybe this whole argument is becoming a macho "my cable is bigger than your cable" thing? There's some compensating going on in this thread. 🤣