I recently picked up a used Yamaha HTR-5790 at a sale. There was no way at the time to test it other than powering up, which it did. Once I brought it home and connected some speakers (Polk Monitor 5jr), I hear some kind of electrical hum from the speakers. It has a constant frequency and level, no matter which input is selected or where the volume control is set. The hum is also present when there are no source devices connected. So far, on the input I checked, it passes signal and seems to play fine. I just don't want to listen to the hum between songs or sections of dialog. I have also tried using a ground lift adapter with no change.
Btw, I only paid $40 for it, so I should have suspected something, but I wasn't able to pass it up. I am hoping it will be a simple repair. I'll keep looking through the manual to see if I find something that isn't set right, but my past experience tells me this is probably something internal to the hardware.
Thanks in advance,