A free-jazz hero who began leading his own bands in the mid-'60s, Sam Rivers was a thrilling multi-instrumentalist who swapped easily between tenor and soprano sax, bass clarinet and many other conduits of expression. As much as he commands the free-flowing melodic lead on “Downstairs Blues Upstairs” and summons squalls of stacked horns on the aptly titled “Bursts”, he holds down 1983's funky live composition “Lilacs” with ringing, fluttering piano. And against unnerving shades of cello, percussion and even whistles, the ever-questing Rivers devotes himself to an entrancingly simple flute passage on the meditative outlier “Bliss”.