Anyone Know Where I should Look to Figure Out This Hum?


http://https//www.dropbox.com/s/faxmop972rok7i1/Noise.m4a?dl=0

I recently purchased a Lamm LP2. First couple days, silent. Now this. It's coming from both sides equally, turning up the volume makes it louder. It's not the cartridge. Noise still there when I unplug the turntable inputs from the phono preamp. It sure doesn't sound like a ground hum and since it's both channels I don't think it's going to be a bad tube . I have another set of tubes on the way but they won't be here until next week so I can't double check that. I swapped out the rectifier tube and that changed nothing. 

Help!
dhcod
I was wrong. It was a ground loop which was solved easily by the first thing I should have tried which was putting in a 2-prong adapter on the Lamm. Done. Noise gone. 
Curious that Ralph said it wasn't a ground issue. While it's common enough to hear 60/120Hz buzzing, I have heard a heavy hummmmm when a lead pops off a cartridge.
Well to be fair to Ralph, there may very well be something wrong. The hum is happening everywhere I hooked it up, including my neighbor the electrical engineer's bench. The solution my simply be covering up the problem, possibly something going wrong with the transformer since my neighbor testing most of the component. I'm emailing all the info to Lamm. I can be patient waiting for a response. Hopefully they will help me figure this out for the long term.
Lamm tech said they found the LP2 to be incompatible with older home wiring and the cheater plug is the fix. It's the best outcome for me, so I'm going with that explanation.
I recently purchased a Lamm LP2. First couple days, silent.
But why the ground loop hum not happened in first couple days?