Coming into the River-to-River Black Moth Super Rainbow show this past Friday at South Street Seaport, I was in a position I don’t find myself in very often these days when going to concerts: I had not heard a note of any of the bands playing. Yes, I’ve seen the names in print many times before: solo artist Dan Friel , from the Brooklyn band Parts and Labor , locals Blank Dogs , led by Mike Sniper, owner of Captured Tracks, and headliners Black Moth Super Rainbow. But I had somehow managed