To quote Apple's own (no longer available) KB-article from 2012 [1]: "In some cases the audio balance may unexpectedly drift towards the left or right channel.

To quote Apple's own (no longer available) KB-article from 2012 [1]: "In some cases the audio balance may unexpectedly drift towards the left or right channel. This can happen if you rapidly press the volume up or down keys while the computer's microprocessor is under heavy load." [1] https://web.archive.org/web/20120630125615/https://support.apple.com/kb/TA22305 https://web.archive.org/web/20120630125615/https://support.a...