Sometimes it saddens me that the memory and the music of Chicago’s singular Hal Russell, who died in 1992 at age 66, have faded so much over the past two decades, because as I see it the free-jazz and improvised-music renaissance here wouldn’t have happened without him. Drummer Steve Hunt, reedists Ken Vandermark and Mars Williams, and bassists Brian Sandstrom and Kent Kessler are all veterans of his mighty NRG Ensemble, and that group’s DIY, go-for-broke aesthetic informs much of the music still produced in town. Russell started out as a bop drummer and in the 50s often gigged in pickup combos backing some jazz’s biggest stars—Billie Holiday, Miles Davis, Sonny Rollins, Sarah Vaughan—but he first made his mark playing an early strain of free jazz in the Joe Daley Trio.