hum in system, ground loon? 60hz?

Thanks Paulwp, I have a Bat VK50SE and a Bat VK60. Electraglide AC cords and Transparent and cardas interconnects. Hum occurs with any source. It's not very loud and doesn't change with volume control. I can't hear it from my listening position, but can within 4 feet or so...

Thanks everyone for your advice. I did recently add video equipment. I'll start unplugging that first, then moving the cords around, I do have everything at 90 degree angles and about inch away from each other. If that doesn't do it, sounds like it's time to go from the amp backwards...THANKS!!!

Ok Jtinn, some progress. I lifted the ground on the vk60 with a cheater plug. No change. Used a extension cord and plugged into a different circuit, with/with out cheater plug. No change. On a whim, I pulled the interconnects from preamp to amp. Hum doubled or tripled. Seems like it is in my amp now. Bad tubes? Old tubes? Something else in the amp? I've had the amp for just over a year now.

Thanks

Hum is the level on both channels. What use alligator clips and wire to short? and which ones are 2 and 3? I think it's time to call my dealer and let him help. Thanks for all the comments!!!