Toroidal transformer hum

Please help.

I have a BAT VK-6200 and I can hear a very disturbing hum coming from the amp. It gets so loud at night that I can hear it from 13 feet.
There is no sound coming from the speakers so therefore I ruled out a ground loop problem.

Please advise.
Several threads exist on this topic. There is the possibility that hum is being caused by DC on the AC power line. This can come from a number of sources, including light dimmers, and certain devices with speed and temperature controls. Do you have any of those devices in operation at night ? Try shutting off breakers one at a time to isolate the source. It is also possible the source of DC could be the house of a neighbor who is on the same power company transformer.
I had the same problem in my last aprtment. Fixed it with a ps audio humbuster. Think I saw one fr sale here recently. But if you buy from ps audio or the similar product from channel islands audio then you will get a 30 day trial period. If it isn't dc on te line, just send it back. Don't recall if there were restocking fees or not.
I had the same problem with my Quicksilver amps.
When I called them they told me if I have them on a shelf to put a carpet under amps and that did fix the problem. It was a vibration causing the hum. Give that a try if it works then you can get something better like a set of isoblocks [cork block] and put them under the feet of your amps!
The amp is sitting on the very bottom shelf which is glass.
That might be the problem.
There is no way that one should be able to here a transformer from 13' away, especially a toroid. Yogiboy may be correct about the shelf agrivating it, but I would assume that the previous posts about DC are along the lines. If you can borrow an isolation transformer, that would be my first thought.
Problem Solved. The culprit was the Christmas tree lights.
Thanks to all of you.

Happy New Year!