Help with elusive hum problem

[Tymish]

Hope this is the right forum for this. I've been going nuts tracking down a hum problem.
I'm using a Tascam MS-16 to a Soundcraft Spirit Studio console. The I/O snakes are balanced XLR to 1/4" TRS shield lifted at one end running at +4dBu operating level. I've unplugged AC to everything but the deck and desk. They're both plugged into the same basic Furman conditioner. The Soundcraft has an external PSU with 3 prong and the Tascam has a 2 prong plug. I've tried different outlets with the same results, also tried AC ground lift. The console alone is quiet. Monitoring Input on the deck is quiet. Monitoring either Sync or Play head I get some loud hum, louder on sync than play. I've noticed that guitars & basses are making a lot of noise at this location. There are a couple radio towers nearby, in fact the guitar picks up spanish radio when the compressor pedal is used. Could the heads of the deck be picking up RF? Any clues?

 

[Tymish]

FYI: After 2 days of lifting grounds, changing cables, reseating cards I found the culprit. I was going to use a passive direct box between the deck and mixer for isolation. As I held the DI in my hand (not yet connected to the deck) and moved the hum appeared. So I scan the ceiling with it. As I passed over the water pipes and whoop there it is! So I've got the hum on the console meters, as I turn more appliances on the hum get's quieter? Must be the ground on the water pipes and current potential or something. We'll be putting a spike in the ground now. Any other advice would be helpful.