Here’s a general guide to some of OS X’s more advanced audio-configuration options. Doing so may be required, useful, or just fun to mess around with, depending on your individual case.
However, as with so many other things in OS X, you can tweak its audio settings-in the Output and Input tabs of the Sound pane of System Preferences-in all sorts of interesting ways if you wish. As with so many things in OS X, the default settings often work just fine with little (if any) intervention on your part: Your iTunes music plays through your headphones, and the built-in microphone works when you need it. You can use a Mac for a long time without ever adjusting its audio settings.
