Bob Margolin has been a leading force in the blues world for more than 50 years now, as guitarist, bandleader, featured sideman, producer, teacher, writer, recording artist, and keeper of the flame. In the last couple years he reprised his iconic 1976 performance alongside former boss Muddy Waters in Warren Haynes’s hugely successful, star-studded “Last Waltz” tribute tours, and won last year’s “Acoustic Blues Album” Blues Music Award for his first all-acoustic album, “This Guitar and Tonight.”