Does this help? I don't have an ipod but found this on the website:
What do I need to start using Wireless iTunes Playback on Sonos?
You'll need an iPhone, iPad, or iPod Touch running iOS 6.0 or higher with DRM-free music in MP3 or AAC format stored on the device itself. The device will need to be connected to your home WiFi network.
Make sure your Sonos system is on software version 3.8.3 and higher. If your device is not capable of running iOS 6, you won't be able to use Wireless iTunes Playback. The Sonos Controller is compatible with iOS versions 6.0 and higher.