Spent a few hours this morning continuing the investigation .... turns out it is a very simple problem to eliminate. The problem is related to how far the unit is physically located from the amplifier that it is connected to. I've been running the deck through a Rotel RA-310 and an AKAI AA-8030 receiver, and they seem to emit mains radiation that the AKAI deck picks up. I had the deck placed on top of each amp. Move the deck about a foot away from the amps and the hum goes
May be it won't pick up as much hum if a connect it to my (much newer) Arcam amplifier ... i'll try it and see.