In addition to AirPlay your Libratone Lounge speaker is equipped with a combined analog/digital minijack/miniplug input connection. It is located right next to the mains switch of your speaker, and is covered by a small rubber plug (for dust protection) when you receive your speaker. Remove the rubber plug and insert an appropriate minijack/miniplug cable and you're good to go.
Remember: In our world wireless always trumps wires so when you initiate AirPlay streaming this overrules the minijack/miniplug connection. Use the Libratone app to control volume on your minijack/miniplug connection.