I am running my guitar and microphone through a blue Audiobox USB into Garageband on my iMac running Sierra 10.12.6. When I plug the Audiobox in, the computer will recognize it, and it will begin working as normal. About two minutes after it has been plugged in and is working, the signal will cut off and will be replaced by a high pitched electronic static whine which will get louder and quieter depending on how how much I strum on the guitar or speak in the mic, etc. For a while, I would unplug and replug the Audiobox but I recently discovered if I go to the Presonus Universal Control application or Apple's " Audio MIDI Setup" application and change the sample rate from 44.1kHz to 48.0kHz and back to 44.1, the problem will cease only to return in another two minutes. I've only seen one question before regarding this problem which was still unanswered so any help would be GREATLY appreciated. I've been having this issue for a while and it's starting to really drive me nuts.