well i get a periodic hiss that gets alittle loud after some time of use the hiss goes away.......and its usually just from one side..i take out audio cord but its still there is this normal?? i have a firebox
could be picking up interference from something... try moving the monitor.. if it still persits it may be a bad amp, have you tried running it off an isolated power supply instead of using the wall outlet? my monitors usually pick up the a/c and hiss if i put them too close to my computers lcd screen.. just a thought.
