My Optimus 4X HD outputs a strange high pitched Noise from the headphone output. It basically sounds exactly like coil whine from a graphics card would sound like. I tried plugging it into 3 different amplifiers to check if its really my phone or the amp i was using but turns out its my phone (I also tried my brothers ipod on the same amp with the same cable and the noise was gone). I am running the latest nightly of CM11 and have no apps or tweaks installed which would alter anything sound-related. This is really annoying especially when there is no music playing, can anybody help me?