Jolida Hybrid humming noise through speakers?

I have 1501RC and when the amp is on, there is quite a noticable humming sound that comes through the speakers. You don't hear it from the amp itself, but throught the speakers. You can hear it from several feet away. I have this plugged into a power strip/surge protector, but my other power amp had no problem. Is this a common thing with tube amps? Is there something that can be done before I send it out for repair? Thanks
Well I changed Power cables, Interconnects, Tubes, and outlets, and it still is there. If anyone knows what this is, or has any advice before I send it out for service It would be appreciated. Thanks
I wish I could help more. My 1501 had no hum at all. My recollection is that it has tubes for the pre-amp and SS for the main amps. It is possibly the tubes. I would try: plugging straight into a wall outlet, into the wall with a cheater plug, try different outlets throughout your house, a different power cord, call Jolida and ask for help. Good luck.
hi jeff, i also have a jolida 1501 that made a humming noise at the speakers. i spoke to mike at jolida and he suggested that the hum might be coming from ground loop noise. he suggested floating the ground by removing the center ground pin on the outlet end of the power cord. quess what, it fixed the problem with no more noise. good luck!
Jeff, I have a 1501a that was sent back to Jolida because the left channel failed. When I got the amp back it had a similar hum, even though none was there before. Much to my dismay, it had to go back. I was pretty frustrated as I was without my amp for a month.

Jolida was great. They sent me a new one and pick up shipping for the old because it left their repair center with the hum