I also made sure the bus bars in the panel were copper. This was not easy, but from the beginning a simple bus bar change is nothing crazy.
A copper grounding electrode conductor, oversized, into several grounding electrodes is a plus for cleaner sound.
Keep the outlet(s) themselves away from any of your inter/speaker wires as well.
Separation of that particular run from any other house wiring is a plus, as the lighting dimmers are especially impactful on the interferance

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There is a service entrance cable that is interesting in its physical character. The ground wire is stranded and wrapped around the hot and nuetral like a coax, but not that complex. May offer a bit more sheilding from other wires in your house.
Use other than metal staples to secure the wire. The metal staples, when overdriven will compress the insulation bringing the 3 conductors closer to each other for further interference.
Run that circuit in a different area (attic instead of crawl) than the rest of you wiring.
The hospital grade outlets are a must. The heavier internal and external parts can be felt/seen when installing and plugging equipment into it. The 10 AWG wire will wrap around these outlets and are able to be tightened without blowing the outlet apart, unlike the $.25 Home Depot outlets.
Check different phase landings for the breaker to see if one is more quiet than the other, you never know.
Have fun.
I have a 100 amp subpanel for my room. I have taken 2 30A circuits for my mono blocks, and 4 separate 20A circuits for the upstream equipment. All copper wiring, panel bus, grounding electrode conductor. All hospital grade 20A outlets with isolated ground. I paid for my own specific 400A service run and my own separate transformer on the utility pole. That was expensive
