To kick off the new year, our music journalist Craig Havighurst offers this in-depth analysis of how two great and sweeping genres - jazz and Americana - can have such different audiences and narratives in contemporary life despite their common origins in the blues. Reviewed are two releases - the 10th anniversary vinyl edition of Esperanza Spalding's Grammy Award-winning Radio Music Society and sax player JD Allen's new and provocatively titled Americana, Vol. 2.