I think these "dedicated circuit" threads always set the standard for misinformation. and much of the information that is correct is cited for the wrong reason. People don't know the difference between physics and code requiremets. Many people want to just tell others that they are wrong, no matter what the answer is. the most common error is trying to equate watts to wire size. If you just use ampacity of the wire, a 250W amplifier is good on 26 awg wire which is good for 2.2 amps on common ampacity charts. Starting to see that it isn't that simple?
So if you're a newbie trying to figure it out, this isn't the place. Good luck. Jerry