Am I hearing things?

To add some perspective to Jim’s (Jea48’s) good comments about voltage drop, if the wiring that was replaced is say 50 feet long and during dynamic peaks the current drawn by the system (and anything else that is connected to the corresponding outlets) is say 8 amps (corresponding to about 1000 watts; the aforementioned Bryston amp alone can draw considerably more than that at max power), the change from 12 gauge to 10 gauge will increase the voltage provided to the amp and any other components that are not powered by the regenerator by about 0.5 volts.

That doesn’t seem like a lot, but I suppose it might make some difference sonically. On the other hand, though, if the line voltage at the OP’s location is already particularly high, and perhaps above what is sonically optimal for the particular amp (for example, in terms of the resulting internal temperatures), I wonder if the increase might be in the wrong direction.

In any event, in addition to Jim’s suggestion about obtaining a polarity checker, it may be informative if the OP were to obtain a multimeter and measure the line voltage at various times of the day and evening.

Regards,
-- Al

Craig most 20 amp breakers are run with 12/2 or 12/3  it's hard enough to wire a receptacle with 12 doing it with 10 is a real pain. My guess is unless you're standing there watching the electrician and you had him run 10 he pigtailed some 12 in the box to wire up the receptacle. 

Thanks djones51 and almarg -- this is very helpful perspective and should inform those on Audiogon who are in the process of configuring their systems.

#10 is used for 30amp breakers and the receptacles for those are 240 not your standard 120 and are made to accomodate #10 wire. Some components are 240 so in that case they would run 10/2 or 10/3. 

I called the electrician and he said it was a 25 amp breaker. He assured me I'm fine. Mike