To output Mac audio via AirPlay, you only need to click on the volume icon in your menu bar while holding the ever-handy Option key on your keyboard.

The good news is that you don’t need any third party software to stream your Mac’s audio output via AirPlay, although utilities like AirFoil offer increased functionality and even Windows support. What about just streaming your Mac’s audio via AirPlay? Since OS X Mountain Lion, users have been able to stream their Mac display via AirPlay, but the icon in the menu bar that controls that feature requires video to be streamed in addition to audio. While it’s easy to use AirPlay for iTunes streaming - the AirPlay icon is clearly visible in the iTunes interface - one area where we frequently get questions is AirPlay streaming for the rest of your Mac’s audio.

Most Apple users are familiar with AirPlay, the company’s wireless audio and video streaming technology that lets users play their digital music on speakers throughout the house, or view their iPad or MacBook display on the family’s big screen TV.

How to airplay from mac itunes