Yamandu Costa and Celso Machado jamming backstage at the New York Guitar Festival's fourth biennial Guitar Marathon at the 92nd Street Y's Kaufman Auditorium, January 27, 2008. This concert was Yamandu's first ever performance in New York. Odair Assad is sitting in the chair, and his brother Sergio walks into the room at one point. WNYC's John Scheafer, guitarist Fabio Zano