How To Transmit Audio To Your AirPort Express With Airfoil

Airfoil will allow you to send audio from any application to the AirPort Express. To do this, first open Airfoil. The main window contains all of the relevant controls for this setup.
The first thing to set is the desired audio source, in the Audio Device popup at the bottom of the window (labled with the number 3 above). This determines what audio will be sent to the AirPort Express. If, for example, you want to send a Real stream to the device, select RealPlayer.
Next, click the Transmit button next to each set of speakers to which you wish to send audio. These buttons are found in the Remote Speakers area, labeled with the number 1 in the diagram above.
Finally, play audio in the source, and it will flow out to the AirPort Express units. The output volume can be adjusted with the volume slider for each speaker. That's all there is to it!

Quick Review
Let's do a quick review of all that send audio to the AirPort Express with Airfoil.

1. Open Airfoil and select your audio source in Audio Source popup (3) at the bottom of the main window.
2. Click the Transmit button next to each set of speakers to which you want to send audio.
3. Play audio in the selected audio source and it will play out through the selected AirPort Express units. Enjoy!