Spotify is a streaming online music service so you cannot download Spotify music, you need a Spotify Music Downloader.
A good Spotify Music Ripper is Tunebite, you should try it, it can record Spotify music streaming and convert the songs to any formats you want, so you'll have your music for listening offline or on every music device you want. I use this tool a lot, the YouTube Downloader feature especially, so now I have many youtube videos on my phone.
Anyway, if you want to see how does Tunebite rip Spotify songs, check this link and you'll have a tutorial back there:
http://audials.com/en...ic_stream_ripper.html
Very interesting thread and good question, zekey!!