Subwoofer has a Hum

I have two Martin logan Descent subs. The one sub has a slight hum, the other one is fine. both are hooked up to my Bel Canto pre2p preamp through rca outputs.
I tried changing the pc, used a cheater plug to by pass the ground. I have all dedacated circuits for my gear. There is no hum in my main speakers which are the ML Ascenti. The sub hum is reduced when I remove the ic going to it. I tried to switch the ic's, use differant outputs on the preamp. I still have the slight hum coming from only the one sub.
Can anybody give me some advice in this matter.

Without knowing what kind of (RCA?) ICs you're using, point the arrows back to the preamp instead of toward the amp or subs. Leave the cheaters on the subs PCs and on the amp(s) PC(s). Do ground the preamp.

I'd still like to know what kind(s) of ICs you're using. Oh yeah, and make sure they cross any power cords at right angles, and don't run them right along the baseboard, they might be paralleling an AC line in the wall.
one of the Cap in power section is gone.Open it up and replace with the new one .You will be allset.
I am using Audioquest dimoundback. If i hook up the ic in mono two to one sub the hum is gone. i seem to only have the hum when i hook up in stereo one ic to each sub. i am using a sound meter to measure the output of the hum in each sub. they are pretty much equal with no ic's hooked to them. When i hook up the ic's to each sub the hum will peg the meter at 60hz 10 inches away from each sub. i would appreciate any help you can give me.

Thank You
Nothing like a hummer. No, seriously, let's see if AGon will let this through (2nd try), while DK ads are rountinely permitted.
In any case, not trying to be a wise guy, but have you tried swapping the subs? If the hum moves with the sub it's the wiring, if it doesn't it's the sub.
It also sounds like there could be some kind of ground loop. Have you plugged them into the same outlet, or swapped outlets?
Get to me offline and maybe I can help. I tired of trying to compete with the DK ads for thread space.
Thanks everybody for your help. I fixed it with Nsgarch suggestion of using two cheater plugs on both subs. I guess I had a ground loop problem. I also changed direction of current flow with My ic's
Thank You
Just purchase a Blue Circle BK-86. It will take care of it and you wont have to unGROUND your equipment.
Cheater plug is the easiest fix...If you don't like the looks of those things try a Monster Power HTPS 7000. I am amazed at how well this unit cleans up the hum.
Get a ground loop isolator, I had the same problem with my sub and my tubes. I got mine from parts express.
"I have all dedacated circuits for my gear."

And therein lies your problem. Plug everything into one circuit and be amazed when the hum suddenly disappears. Try it and let us know. I'd be very, very surprised if that didn't solve your problem.