Add background music to all my levels

I’ve made 10 levels, each a separate scene, and now I need to add the same background music to each. Obviously I could open each and add an audio source but that seems time consuming and inflexible (say I wanted to change it etc). Is there a way I can add background music in script?

http://docs.unity3d.com/ScriptReference/AudioSource.Play.html

Music Singleton :

I think if you create an empty gameobject, attach the audio to it and add a script that calls dontdestroyonload. You should get what you’re looking for.