"It stands to (my) reason that the surviving source of the songs would be the 'source singer', n'est-ce pas?"

I'm no singer, but if I ever poke my head over the parapet at my local sinaround (the Beech, Chorlton, 1st & 3rd Wednesdays), my source is my record collection... Luckily it contains stuff like VOTP and various Veteran and Musical Traditions CDs. I would suggest that this is the problem of calling "traditional" singers "source" singers...

I usually find it fairly obvious which are chorus songs and which aren't. Comments like "please join in on the chorus provide handy clues, too"...