I went to the apple store last week to have my iphone replaced and decided to test out all the computers on display. I've noticed my personal computer will vibrate/buzz when the 'hero' tone is played, and only through the right speaker. Every computer on display at this particular apple store had the same issue. I also asked the Genius at this store, and he made a note of it and said if they all do it, apple will likely make a fix for it to correct the issue. Test yours and post results... What I did was go to the System Prefs, under 'Sound" and turn the alert volume all the way up, and the computer volume all the way up as well and play the 'hero' tone. I noticed that some of the computers were worse than others with mine being on the lower end of the scale... however, I'd expect a computer that costed as much as this to not have issues like this. I'm not going to return it, or complain until something comes of it, I'm more or less convinced that its 'normal' at this point. Post your results! (yes, I'm aware that there are other threads on the topic, but nothing really for people posting results from a uniform test on it.