Turntable Hmmmmm

I could use some advise, here, please. I recently bought some new equipment and have been setting things up a bit at a time. I have a McCormack DNA-225, Kora Eclipse preamp, a Sony CD player, a Pioneer CD recorder, and a old Sony analog tuner all hooked up and running fine. Then, I introduced a Nottingham Spacedeck TT with Tracer #3 cartridge to the system. I had the TT and cartirdge in an another system with no problemes at all. Now, in this system, I get a very low frequency hum, barely audible at low volumes but which gets progressively louder as I add gain to the preamp. Amp and preamp are connected to one wall outlet, the rest of the components on a power strip run through a second outlet (neither dedicated). I have checked the RCA connections, the ground connection, moved the ground, swapped out outlet connections in every combination, and tried a cheater plug - all to no avail. Anyone have a sugestion on what to try next? Thanks