When I connect to an HD TV using the Mini DisplayPort (via a Monoprice Mini DP-DVI dongle and a Monoprice DVI-HDMI cable) and to a Hi-Fi system using the headphone out, the Hi-Fi speakers emit a loud and persistent high-pitched whine. The whine disappears when I disconnect the Mini DP dongle, and also when I disconnect the audio cable so that the sound is playing through the internal speakers. There's no whine when I connect earphones to the MBA instead of the Hi-Fi. I don't have another external display with which to test the issue, so I'm not sure if this sound exists when the computer's connected to, say, an ACD. I'm surprised that this problem doesn't seem to have been mentioned on this board, but it's well documented on the Apple boards (1, 2, 3, 4). The consensus over there is that it's a fundamental design flaw in the MBA and that the only solution is to get a ground loop isolator. Has anyone here had the problem and been successful in getting it fixed by Apple? The reason I ask is because my MBA has fallen victim to another common audio problem for which I may need to bring it in for servicing, and I am not sure if it would be a waste of everyone's time to have them attempt fixing the problem.