I am experiancing an intermitant humm/buzz through my speakers when using my turntable. When I turn off the turntable, the buzz persits. When I move the pre amp selector switch off the phono MM position, the humm stops. Sometimes the Humm comes on loud and other times the volumn must be turned up and the humm increases with volumn. There is a phono MC Position, but the specifications state that the cartrige is a moving magnet type and I have always used the MM position and connection.The turntable is a JVC QL-A7. The preamp is a Mitsubishi DA-P20. The amp is A Mitsubishi DA-A15DC. All three are circa 1980. The turntable has been rarely used over the last couple of years and therefore the phono selection position hasn't either. I've recently gotten back into listening to my vinyl and would love to get to the bottom of this. Any advice/suggestions would be greatly appreciated. Thank you, Richard
