The scene at Tipitina’s that Monday night is typically insane. It’s the end of the annual WWOZ Professor Longhair Tribute/Piano Night during Jazz Fest, and show-closer Eddie Bo has, in a gesture of his usual charity, brought up many of the night’s earlier performers to cluster at the two dueling baby grands for an incendiary, twelve-or-so-handed show closer. It looks like a happy riot in a lunatic asylum music room.

Sharing one of the pianos with Bo is Marcia Ball, whose own set—directly p...