I had an upgraded home theater power line put in when we bought our 1962 house a year ago. We had to replace the whole electrical wiring system based on age: NOWHERE near current code; age of the wires and the breaker box; size of the wires, nothing but the breaker box was grounded, most outlets had only two prongs, those with 3 weren't grounded!. <shudder> Scary!
We ran 20A Romex everywhere for the 110VAC, but used 15A breakers, except the home theater got a 20A breaker. I don't know if there is an audible difference because all the work was done before we moved in last year. But I know the shared 15A circuit we had in my condo wasn't cutting it. I had to make sure the lamps, clocks, everything and anything else was on a different circuit to keep from popping the breaker. Movies or music, no problems. And since it was done as part of the whole house rebuild (power, water, HVAC), the cost of one breaker upgrade is insignificant.
We ran 20A Romex everywhere for the 110VAC, but used 15A breakers, except the home theater got a 20A breaker. I don't know if there is an audible difference because all the work was done before we moved in last year. But I know the shared 15A circuit we had in my condo wasn't cutting it. I had to make sure the lamps, clocks, everything and anything else was on a different circuit to keep from popping the breaker. Movies or music, no problems. And since it was done as part of the whole house rebuild (power, water, HVAC), the cost of one breaker upgrade is insignificant.