You could add a power conditioner at the breaker if you wanted to get fancy, and I'd call it a dedicated circuit as is. If your lights are incandescent you might try listening with one or more on, a constant resistive load (good old fashioned light bulb)can sometimes improve power quality by shunting noise line to line.
Dedicated circuit = dedicated line?
Will installing a dedicated AC line into a music room provide any benefits over the dedicated circuit now in the room? To explain - my room has three outlets and a ceiling light shared on the same 15A breaker circuit with a hall outlet and ceiling light. Nothing else is plugged into any of the outlets except for my audio equipment. The overhead lights are always off during music listening. Does the fact that multiple outlets and junction boxes exist on the circuit in and of itself result in "degraded" AC power delivered to my audio componets? If so, could something be done at the breaker to appreciably improve the dedicated circuit quality without having to incur the expense of adding a separate AC line into the room?