In my case, there are no other electronic devices near my HT equipment. Bringing down the noise level in its immediate area is being handled by my PS Audio Ulitimate Outlet, an APC H15 Power Conditioner, and a Mondail Magic Coax Ground Isolation Device.
The final step is the shielded 2-wire IEC power cord connections to the equipment itself.
I can't/won't mess with the 3-prong devices, and will not modify the equipment that does not have detachable power cords.