I have a Line 6 Pod HD500 connected with USB to my computer. When I record hi gain stuff there's some noisy signal at 3000 Hz and 6000 Hz. You can hear it in the audio file found here: http://picosong.com/wkCAU Today I noticed that if I click a mouse button or a key on the keyboard, the beep/noise gets momentarily louder. This is also audible in the audio file. The mouse and keyboard are also connected using USB. No USB hub involved anywhere. Does anyone know what this is or at least have a theory and know how to get rid of it?