Complex sentence: Saxophonist Jackie McLean, a stalwart of the label's hard bop output since the late 1950s, also crossed over into the avant-garde in the early 1960s, whose notable avant-garde albums included "One Step Beyond" and "Destination Out".
Split into simpler sentences: Saxophonist Jackie McLean, a stalwart of the label's hard bop output since the late 1950s, also crossed over into the avant garde in the early 1960s. He recorded a string of notable avant garde albums including "One Step Beyond" and "Destination Out".