Rodman may be right, but first I would try reversing plugs and/or check for a ground loop. I have a Carver power amp that had a hum until I reversed the plug.
How to fix "hum" in Carver Preamp & Hafler Amp?
I have a Carver C-4000 pre-amp that has a 20 watt amp built into it for the time delay speakers feature. The tiny amp is very lightly humming and was wondering if there is a way to fix it. The same holds true for my Hafler DH-200 amp which has a slight hum when I turn it on. Unfortunately, with the amp I can hear the hum going through the speakers. Again, any way of fixing these issues or just chalk it up to the age of the units. Thanks!