When you consider his mercurial youth as a rock 'n' roller turned fusion guitarist--a period marked by musical excess as well as energy and craftsmanship--it's hard not to grin at Larry Coryell's measured passage into middle age. On one recent album he joined forces with his two grown sons, all of them on acoustic guitars; on another, the 1997 Spaces Revisited, featuring fellow 70s fusion god Billy Cobham on drums, Coryell gracefully augmented his old music's original thunder with mature illumination. But these days Coryell mostly explores the mainstream jazz repertoire or his own smart originals, accompanied by unimpeachable veterans of the 60s postbop style. (These musicians include pianists John Hicks, Ronnie Mathews, and, on Coryell's most recent HighNote disc, Cedars of Avalon, Cedar Walton, whose work helped distinguish Art Blakey's Jazz Messengers throughout the 60s and 70s.) I love the way Coryell handles traditional tunes, how his solos inflect hard-bop language with his own idiosyncratic phrases and accents, particularly with his Chicago-based trio, which I find the headiest of his ensembles. When Coryell came to play the Jazz Showcase in the mid-90s, owner Joe Segal suggested he hook up with bassist Larry Gray and drummer Paul Wertico; since then, Coryell has worked only with these guys when in town. He eventually recorded an engagement at the club and released it last year as a private-label gem, Live in Chicago, and he's taken Wertico (and a different bassist) on the road with him. Though they've played together mainly on a same-time-next-year basis, these three have developed a spectacular group dynamic, with Gray acting as ballast to the destabilizing forces that Coryell and Wertico occasionally generate. To my ears, it's Coryell's most satisfying music in a decade. Friday and Saturday, January 10 and 11, 9 and 11 PM, and Sunday, January 12, 4, 8, and 10 PM, Jazz Showcase, 59 W. Grand; 312-670-2473.