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.
Have you tried a transformer for the cable TV line? Jensen makes one that supposed to get rid of cable TV-induced ground loops.
Hi Ken, the ps 300 is part of my system i could not due with
out. I picked one up last year, i dont think it will fix
your problem . On my tv set up with out ps-300,had to
lift the ground on my amp and preamp, was getting ground
loop from cable line because if disconected cable hum
was gon. Try cheeter plug's on amp and preamp,i dont
like to do this but it workes.
I had the exact same problem, which was solved by one cable TV guy who knew what to do (no jokes about morons, oxy or otherwise).
He sent me to Radio Shack to get a 75-300 ohm adapter. It is not the one they sell as a "filter," merely an adapter. (I tried the filter and it doesn't help.) I wish I had the part number, but it's not on the piece. It is about 6" long total. It has the male part of the coax as part of a 2" rectangular rubber piece with 4" of antenna wire and two spades extending from it. Then I connect it to a standard plastic antenna to coax converter, which has the terminals for the spades and the female coax. I don't know why it works, it's not made for this purpose, but it does. I have no more hum. When I take it off -- hum! (Hmm?) It costs less than $5. If you can't find it, post here and I'll try and check at Radio Shack for the part number. I hope it works. The cheapest solution to a BIG problem I ever found!
I use the 'ground breaker' on my TV cable between the wall and the TV. I ordered it online from these guys and it works great:

Near the bottom of the page:

Xanatech 63400 Ground Breaker $6.95 each
If your cable TV ground is near the electrical service entry ground, tie them together. This should put them at the same potential and minimize any hum. I don't see a problem with doing this, but it might be good to check with a licensed electrician.

"OH GLEN, where are you ???" : ) Sean
Just been thru this -- Same issues only with a ARC LS-25... My problem was due to 3 issues -- Corrosion on the ground rod and connection to cable ground where cable TV comes into the house (replaced the ground rod and all connection hardware); Found the particular outlet for my HT had a lame connection (grounded with outlet contact to conduit; fixed by purchasing a grounding strap from the hardware store and making a more solid connection); The house ground had alot of corrosion on the water pipe (got new connection hardware and cleaned up the surface with emory cloth); Tied the cable to the outlet ground by using a Monster HTS-1500 power conditioner for the RPTV. After all of this, the ARC is dead silent, the video is perfect, and my stereo has more detail than ever...

Just some things to look at..
As PS Audio gives a 30 day in home trial why not order one and find out. It did wonders for my system. In fact I bought 2 of them.
(PS: I dont work for PS Audio!)
I had very bad hum when I first combined my cable and home theater system, I bought a Mondial Magic box which cured the hum, that was 3 years ago and it has not left my system since!
Let me add my 2 cents on the P300...I've had mine a year and couldn't part with it. It's worth mentioning that the P300 has a RF coax in/out connection on the back (which isn't even mentioned in the owner's manual) that apparently is some kind of isolation device. I route my cable TV through the P300 using those connections, and it completely eliminated my hum problem. If you decide to buy used, make sure you're getting the multiwave makes a significant improvement.
I believe you have several possibilities to resolve the hum.

1. Disconnect all grounds for all equipment and/or
2. Ensure that all equipment is running off the same circuit as the tv/vcr, etc.. Your sonics and equipment especially your amp will suffer as a result or

3. Ensure that all components are running off the same phase of 115 volts at your service panel.

Disconnecting the ground on all outlets should cure the problem while also providing greater sonic benefits since the ground has a way of introducing additional AC noise into the components. In the long run, I would perform 1 and 3 and you should never have a ground loop hum again.