Applejelly, Did your problems with ground hum start when you purchased the VCR? I notice the antenna runs through it first. As one ‘elimination’ step to reduce your probabilities, - you might attempt bypassing the VCR completely on the chance there is an interaction centered in that unit, before digging deeper, into power conditioners etc?

I had my old JVC with the 950, before the 60” display for several weeks, (also in use before I added the Panamax) with no problems.