Kenwood DNX525DAB Playlist Format

Hi,

I've been using a DNX525DAB head unit for almost a year now, but I haven't managed to make a working playlist for any of my music files.  I'd like to create a few for when I've got different people in the car - mostly Elvis for my Mom, classic rock for my Dad, and Rat Pack & classical for my mother-in-law.  I've tried using m3u and pls files using relative paths from the location of the playlist file, and I've tried other formats although I can't remember which ones now.

Has anybody had any success with this?