For my system, which is computer-based, I have a dedicated 12 gauge line powering the DAC and power amp only. It's regular Romex wire, nothing special.
The computer itself and the external hard drive are powered from a separate circuit, but not a dedicated one.
This significantly improved my system relative to the previous setup, without a dedicated line. Now I don't use a power conditioner anymore and the improved dynamics are delicious.
As far as the phase question, if more then one dedicated circuit is used, it's recommended that all of them should draw from the same rail in the breaker box. This will bring them "in phase".
The computer itself and the external hard drive are powered from a separate circuit, but not a dedicated one.
This significantly improved my system relative to the previous setup, without a dedicated line. Now I don't use a power conditioner anymore and the improved dynamics are delicious.
As far as the phase question, if more then one dedicated circuit is used, it's recommended that all of them should draw from the same rail in the breaker box. This will bring them "in phase".