Hum in Speakers with New Dedicated 20 amp Circuit

As Erik expressed, somewhere within your system you are picking up the ground noise. Try a plug cheater adapter to lift the ground just to see if hum goes away.

If that does not help, try disconnecting cabling that comes from other sources outside your new dedicated line.

ozzy

Are you sure that no component connected to your system is plugged into an AC outlet other than on this dedicated circuit? That could create a ground loop through interconnect cables.

Winner Winner Chicken Dinner!  Ground loop…duh!  I had the stereo rack plugged into the new, dedicated circuit, but I had the subwoofer plugged into a separate outlet that was not on the same circuit. Moved the subwoofer over to the dedicated circuit and…viola… no hmmm. Thanks all!  

This is a sub panel.  Ground and neutral should not touch here.