Apple AirPort Express 5.1 - Manual (Page 18)

18 Chapter 2 Using AirPort Express
There are also other ways you can connect your AirPort Express to your home stereo.
If your computer has an AirPort Extreme Card installed, or a compatible wireless card
for Windows, you can use AirTunes to play iTunes music on a stereo connected to your
AirPort Express.
DSL or cable
modem
to Internet
Stereo receiver
Line Out port