I was thinking about the thread concerning the stage performances of
 Lester and Earl using a single mic.  First  time I saw Flatt and Scruggs 
 my parents  took me when I was 5 or 6 to a show in Gassaway, West
 Virginia (56-57).  Funny thing was that was at the drive-in theater, Flatt
 and Scruggs were  playing on top of the snack bar....
 We parked facing the snack bar, as everyone did, and instead of
 applauding the folks flashed their lights and honked their horn.  The
 sound was coming in through the little funky speaker stuck in my dads
 jeep window.
 I was not really a BG kinda guy yet, so while playing tag with my
 friends I remember thinking, "howd that they get that big thing
 (doghouse bass) up there?"   seemed so big on top of the snack bar
 to a guy my size then.  And yes, they were singing around one mic
 with a wire going into the window of the projection room.
 As a side note, I met Lester years later backstage at Bean Blossom,
 probably 73-74, and mentioned the snack bar performance, and he chuckled
 and said, "You know son, in those days it was the only place in lots of
 towns through out the south that had room enough for us to play",
 (because of the crowd they could draw). Lester was very gracious and we
 talked for sometime.  One of the most precious moments of my life.
Thanks to Mike Baughman for this trivia!