How do I eliminate FM interference and low hum?


I just completed a Curcio Premium mod on my Dynaco ST-70 and it sounds great, other than a slight hum and the local mega watt country station bleeding through! I tried unhooking all IC's from my preamp except the ones to the amp and it's still there. Even when I turn off the power to my preamp it's there. When I remove the IC's to the preamp and install rca shorting plugs both the hum and the FM disappear. It seems as though my IC's are acting as an antenna.
My preamp (for now) is the preamp section of a Marantz 1120 integrated amp, I have a Granite Audio tube CD, a Marantz 2110 tuner, a BC music ring and use Buggtussel Amygdalla speakers (91db sensitivity). Prior to this setup I was using a pair of Granite Audio mono blocks and a Granite Audio 760 preamp along with the BC music ring and the Marantz tuner and had neither of these noises coming through my system. Is there some way to modify my IC's or can something be added at the inputs of the amp to filter this noise out? Thanks a lot for any and all suggestions.
nelsress
Put a small capacitor like .47uf/50V from RCA output gound to the body of your preamp chasis.
This the ground loop problem in your preamp. Probably bad grounding point somewhere.
This should do the trick.
Thank you S23chang, that's an easy enough fix, I'll give it a try, perhaps this weekend.