I just got my Sonos and realized can't use my Spotify free account on it! I really like the Spotify app, playlists and everything. Was a premium user until they made the app freely available. I have also tested Google Play music but it does just not pack the punch spotify does for me.
Considering going premium again. Unless if there are any other music streaming service that can be paid with my Telstra Bill that might be worth trying.
Why don't you just youtube your favourite songs and download the mp3?