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.
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