Not strictly a DIY question but I though someone here may be able to help! I am suffering a faint hum in both speakers attached to my integrated valve amplifier. \r\nSome features of the hum:\r\n[LIST]\r\n[*]I can only hear it when my ear is quite close to the speaker (and there is no music!)\r\n[*]It sounds like mains frequency. \r\n[*]It is present in both channels even when there are no other devices attached to the amplifier.\r\n[*]It is not at all affected by the volume, even at max it is no louder.\r\n[*]It is present whether or not the ground wire is connected in the plug\r\n[*]It is present when all the valves are swapped\r\n[/LIST]\r\nAny help in eliminating it would be gratefully received!