Import playlist for conversion.

Use case
Create a playlist of my top rated songs in Rythmbox and export it to playlist.xspf Then import that playlist into SoundConvertor (import file) so the songs can be converted from Flac to mp3 for my car stereo.

I have tried this with .pl .m3u and .xspf and none of them have worked....also none have thrown an error. (Actually in the terminal it says it isn't an accepted mime type.)