8.1.0 Playlist location?

I've somehow lost my playlist data but have backups of the .M3U files used.
Please can anyone advise the stored location so I can manually restore them?
I thought I'd found it in /slimserver/prefs but a rescan didn't find them.
I'm using PCP 8.1.0 and LMS Server Cache and Preferences are to the Mounted Drive.