If it isn't immediately recognizable to anyone curious, this is an atypical Billy show, with it being deliberately an "old timey" bluegrass throwdown. This recording of such a show is superbly done, as it captures the wonderfully played music which you can clearly tell the boys had fun delivering, but also how much fun the crowd was having. Big Sandy River > Little Maggie... hot damn, what a hot transition, and the crowd clearly LOVED it.
FWIW, I'm not of the "bluegrass only" crowd which Billy attracts, as I'm primarily here for the long, drawn out acoustic jams. This is just that good of a show.
