I bought a paid of Eris 4.5 speakers about two years ago and right as the warranty expired they started to emit a static noise from the volume knob, when i turned the volume knob to increase the volume there was a static crackling sound then it would stop. Shortly after that i noticed that the power would take about 10 - 20 seconds to start up and there would be no sound until the speaker powered up and the blue light came on, this got longer and longer over the next couple of months until the speaker would not power up for over one hour after turning on.
I took the speakers to get fixed and they are working ok again. However these speakers have always had an issue with any TRS cables plugged into the back, even if i just plug the cables into the speakers but dont plug the other end of the cables into anything else like a mixer, they start to emit a pretty loud hum.
I though that this was an issue with my ********* mixer, so i started unplugging the cables from the mixer when i was not using it, but leaving the cables plugged into the back of the speakers, but i still get this pretty loud hum like static build up with just the dead cables plugged into the back, the noise stops when i unplug the cables from the speakers.
It seems like its some kind of ground loop, but its odd because i did not use the mixer with the cables into my speakers for weeks now, so its obviously an issue with the input for these speakers.