Thanks for the tip ytechie!!!
I took a look at the subsonic.script file just to find it was somehow truncated (it contained just a couple of lines!!)
So I moved /var/subsonic to /var/subsonic.old, reinstalled the .deb package, started the service, and once I saw it was running again I stopped it and moved the script file onto the broken one. Undid the .old folder renaming and started the service again. I had the idea that this would probably get back my config, but nope, had to reassign the music folders and re-create the users (fortunately I have only two at home)...
Thanks again, it is back and rocking! (literally

)