For anyone who has a large (60+K) music library in iTunes but are running into the size limitations in Sonos. I wrote a Visual Basic script that is run from within MS Access that can export select playlists in iTunes and the corresponding audio files to a separate location indexed by Sonos.
It currently exports to the WPL (Windows Playlist) format because it accommodates foreign characters unlike M3U (apparently the unicode M3U8 isn’t supported by Sonos).
I previously used iTunesExport, but it stopped working once my iTunes library started getting north of 100,000, so I decided to take matters into my own hands.
If anyone is interested, I can give you pointers on how to to set it up and share the script. It does require building a table which lists all of the playlists you want to export but once that’s in place, it’s a huge time saver. For efficiency, it even skips overwriting files multiple times if they were already exported by a previous playlist.