The current jazz climate's strong emphasis on the music's past has fostered a batch of jazz repertory orchestras, with the Chicago Jazz Ensemble emerging as the genre's Brigadoon: it reappears every so often after long absences. Directed by William Russo, the respected composer who runs the music department at Columbia College, the CJE's current program offers a typical mix: one Jelly Roll Morton tune, a few from the Basie band, several from the Stan Kenton Orchestra (to which Russo himself contributed some of the most influential pieces), and an entire second half devoted to Russo's hero Duke Ellington, including some relatively obscure works. Russo reveals himself as a musical perfectionist in the ensemble's performances, peppering his hand-chosen ensemble with powerful and ear-grabbing soloists; this time around, he features trumpeter Orbert Davis, saxist Ari Brown, and the lesser-known, giant-toned trombonist Audrey Morrisson, as well as two impeccable vocalists, Carol Loverde and Bobbi Wilsyn. But Russo does more than conduct. He also lists himself as director and executive producer of these concerts, which feature elaborate costumes for the vocalists and a couple of questionable choreographed numbers. The singers and dancers appear from both sides of the stage, and even on a raised platform behind the sharply tuxedoed band; Russo apparently means to emulate the elegant New York nightclub shows of the 30s and 40s, but presented in a smallish theater in the 1990s such maneuvers suggest an overly ambitious college musicale. Fortunately, the music and its execution rise above the trappings. Friday and Saturday, 8 PM, and Sunday, 4:30 PM, Getz Theatre, Columbia College, 62 E. 11th St; 663-9465 or 559-1212. Wednesday (with the Grant Park Symphony Orchestra), 7 PM, Petrillo Music Shell, Grant Park, Columbus and Jackson; 819-0614.