When saxophonist/drummer/trumpeter/visionary Hal Russell died in September 1992, the future of his NRG Ensemble was certainly called into doubt. Then at a memorial tribute a few months later, NRG took the stage with multiwind player Ken Vandermark in Russell’s place, and the group hasn’t looked back. De facto leader Mars Williams may lack the vaudevillian panache with which Russell charmed his audiences, but musically the group has taken its founder’s basic ideas and sharpened them to a deadly point. A handful of appearances since Russell’s death have revealed a wealth of new material and a reignited spark, the greater precision of Vandermark galvanizing NRG by trimming away the fat that lingered under Russell’s leadership and tightening the complex arrangements. The group has just released its first post-Russell recording (which does include three tunes from the immense Russell book), the burning Calling All Mothers (Quinnah). On it the whooping, screeching, squealing, and interacting horns of Williams and Vandermark ride over the impossible free-jazz rhythms banged out by drummer Steve Hunt and bassist Kent Kessler, while multiinstrumentalist Brian Sandstrom colors the barrage with caustic, Sonny Sharrock-ish electric guitar drizzle, tart trumpet smears, or the thick prodding of a second bass. It’s a remarkable album–aptly proving that NRG has retained Russell’s vision while brashly forging ahead–and the ensemble’s frenzied live gigs are no different. Thursday, May 5, 8:30 PM, HotHouse, 1565 N. Milwaukee; 235-2334.