does Spotify play a local file if it exists?

Question

If I have a local copy of a song, does Spotify still stream it or play the local copy? Or does it choose the one with higher quality of the two?

By local copy, I mean a MP3 that I ripped from disc or something

Answer 1

Only 8.8% of music playback comes from Spotify’s servers. The rest comes from the peer-to-peer network (35.8%) or your local cache (55.4%).

http://pansentient.com/2011/04/spotify-technology-some-stats-and-how-spotify-works/