Hum and the PS Audio P300

I've had a hum in my system for several years. Its no mystery. Its caused by the different ground between my stereo (house ground) and the grounding of my Cable TV's (AT&T Broadband)ground. I've tried spliters and the little box with cable connectors on each end and a dedicated ground. None of that works. I upgraded from a ARC LS2B to a Sonic Frontiers Line 3 and the hum dropped 10db so I've lived with it. The question is I'm considering the purchase of a PS Audio P300 power plant for my CD and preamp's power. Can I expect the hum to go away or get worse? I can terminate the hum totally if I either disconnect the TV cable or isolate the DVD player which is connected to the TV from the preamp.