So does it make an AM jock sound like an FM jock? Sorry. I have never heard of this but here are a few scenerios. If you have Directv or dish sometimes that can feed it to a household. Mine was in my cordeless phone. Possibly if you have Sat TV you might try disconnecting the power cord, coax,and phone connection from the DSS reciever and see if the "little voices in your sub" go away. If that is the case it is probably either feeding back through the a/c if they are plugged into the same circuit. If not then it is through the interconnect. If this proves to be the case
there is a filter that plugs into the telephone connection
and filters out the RFI. If not I am not sure what else I would look at, a sub is a crossover, amp and speaker, can't imagine how it could become a tuner. One other thought, if haven't tried disconnecting the IC and observing the loss of the AM sound, try that it. If so it may be in your processor, especially if it a receiver.