A dedicated circuit is the best way to go. The Nation Elec.Code (NEC) has changed it's grounding requirements over the years. So it depends when you house was built or updated what kind of grounding you have. Also different States ,Counties and Cities have varying requirements. What you need is a dedicated ground and neutral to your System. The neutral is a current carring ground. It will transfer noise. Also if your electrical panel has a bonded ground the neutral and ground are connected at that point (carries noise). You need to "float" your ground to your music system. Talk to your electrician when installing a dedicated circuit about isolating you neutral and mechanical ground.
