Krell KAV300i help

I just bought a Krell kav-300i on Audiogon. It works great, just one problem. I hooked it up to my Marantz sr5300 receiver using the Theater Throughput input to watch a movie but there was a very noticable hum from the speakers. It works perfectly hooked up directly to my cd player. I'm using the front L/R preouts on my receiver and I have selected "proc" inside the Krell.
Any help anyone could provide would be greatly appreciated.
Sounds like the dreaded ground loop issue. Try unhooking any cable tv connections and see if this helps - if not try removing one item after another in the chain. Hopefully you will find the unit coursing the problem..
Also, experiment by plugging your receiver into the input now used by your CD player (which you already know does not hum) See if you can still get it to hum. If so, it is your interconnects, or your receiver or the 'improper grounding' monster.
Thanks for the help. It turns out that it was the cable tv. I had everything, including the cable tv, running through a Monster HTS 1000 power bar. Just a couple of days ago I disconnected the cable tv from the power bar and ran it staight to the tv until I could buy a longer cable to run from the power bar the tv. So now I tried running the cable tv through the power bar again, and wouldn't you know it! So these power bar/cleaners actually do work. Thanks again for the help!