For many devotees, Charlie Haden is a hero of the post-bop era: a double-bass virtuoso renowned for his lyrical style and refined taste. For others, however, he is first and foremost a leader of the genre’s avant-garde, a bold improviser who expanded his instrument’s harmonic potential as he worked with some of jazz’s most experimental artists, including trumpeter Don Cherry, pianist Carla Bley, and, of course, the one and only Ornette Coleman.