If this helps it will be less work.
Before running Romex, I would open the outlet box, the closest electrically to the incoming power, and check all the connections. Then follow the lines to boxes going back to the panel, or coming from the panel, and check those connections. Tighten or re-do when in doubt. if there is no separate ground wire, a poor conduit connection somewhere may be the cause.
I had one customer where the cable TV ground where the cable entered the house LOOKED proper but did not actually electrically contact the pipe it was on, and the system got a hum (though that may have been only when using TV. ) I fixed the connection so it actually grounded and the hum disappeared.
Another had a cable box and a modem in proximity, and I ran a wire from the cable box case to the outlet box (ground) to kill the hum.
A friend ran a wire between two of his components' chassis to kill a hum or noise.
Before running Romex, I would open the outlet box, the closest electrically to the incoming power, and check all the connections. Then follow the lines to boxes going back to the panel, or coming from the panel, and check those connections. Tighten or re-do when in doubt. if there is no separate ground wire, a poor conduit connection somewhere may be the cause.
I had one customer where the cable TV ground where the cable entered the house LOOKED proper but did not actually electrically contact the pipe it was on, and the system got a hum (though that may have been only when using TV. ) I fixed the connection so it actually grounded and the hum disappeared.
Another had a cable box and a modem in proximity, and I ran a wire from the cable box case to the outlet box (ground) to kill the hum.
A friend ran a wire between two of his components' chassis to kill a hum or noise.