The discography of Larry Coryell–at 57, still one of the most gifted and fascinating guitarists in American music–is almost as varied as his mercurial, muscular improvisations. In the past five years alone, his releases have ranged from a solid neofusion effort, Spaces Revisited (Shanachie), to an awfully good solo acoustic album, Private Concert (Acoustic Music), to last year’s New High (Highnote), which augments a traditional piano-bass-drums rhythm section with trumpet and vibes. (He also put out The Coryells, on the Chesky label, which features him, his two sons, and his wife all playing guitars–for me, at least, a validation of the decision never to attend other people’s family reunions.) But Coryell’s best working band remains a group he’s yet to record–his “Chicago trio,” which he first assembled for a Jazz Showcase date in the early 90s and re-forms every time he comes back. The band stars Larry Gray, whose blend of big sound, demonic technique, and musical sensitivity makes him arguably the best bassist in the midwest; and drummer Paul Wertico, whose many years driving the Pat Metheny Group have made him especially well qualified for this job–Coryell’s own fiery work at the dawn of the fusion era offered an early model for Metheny’s playing. In this setting, though, everyone keeps his virtuosic strengths in reserve, and in that way the trio works like a powerful stereo system, where the wattage makes the music sound better even at low volume: when these guys play simply, it’s clearly because they choose to, not because simple is all they can manage. On each of Coryell’s more or less annual return visits, this band has refined its interplay, and its ever-deepening repertoire reflects both a familiarity with the Great American Songbook–a sort of lingua franca for jazz musicians over 30–and a predilection for referencing rock ‘n’ roll or fusion when the music calls for it. As far as I know, Coryell uses the trio format only in Chicago, making this band pretty much unmissable in my book; even if he put together a similar group elsewhere, I doubt he’d find the same simpatico connection with his sidemen. Friday and Saturday, February 2 and 3, 9 and 11 PM, and Sunday, February 4, 4, 8, and 10 PM, Jazz Showcase, 59 W. Grand; 312-670-2473.