I use a single dedicated 20 amp circuit for my audio and video equipment and there has never been an issue with the amount of AC power. However my subwoofer is off a 15 amp circuit that predated my remodel and family room HT. I couldn't locate the sub near the 20 amp outlets due to room constraints. I ended up with a ground loop caused by the different ground used for the cable box and induced a hum in the sub. If I had it to do again I'd add an outlet for the sub from the 20amp circuit. I don't know if that would have solved the ground loop caused by the cable box but it might have.