It depends. I noticed a difference when I moved to a dedicated circuit at my old house because I had been on the same circuit as the kitchen - having the microwave and the fridge's compressor on that circuit introduced some limitations and noise on the circuit that were reduced by my Panamax and eliminated entirely when the dedicated circuit was added. In our current house, the system is on a circuit that serves the rest of the den and I've seen no reason to add a dedicated circuit for it.