I have a Harman Kardon 3490 receiver that has just what seems like white noise coming from all speaker channels. No matter what input I use OR which brand of speakers I use (all 8 ohm) I hear just what appears to be white noise. At zero volume there is no noise. Anything above zero volume, the noise is heard and does not decrease or increase as I turn the volume up and down. The fuse is good as I have checked that. I have already done both types of resets as per service manual with no success. It did reset but no change in the noise. My son borrowed it for his get together with his friends and told me that he connected one speaker and he could hear the music fine but then when he connected the other speaker, the music stopped and the unit shut off. When he turned it back on, there was only this white noise. I asked him the million dollar question as to whether or not the receiver was powered on when he connected the speaker wires and he reluctantly told me yes which would lead me to possibly think that this may have caused a problem.\n\nI also tried connecting a cd player and bluetooth device to the receiver and still nothing audible except the white noise which as I said before is at a constant volume no matter what volume setting yo have it at.\n\nAny ideas as to what may be the problem and where I should start looking first? I’ve been searching for a couple of weeks now as time allows , but haven’t found anything where someone had white noise problem that was at a constant sound level with no audible music at all.\n\nThank for any input or guidance.