As a professor at the University of Chicago and composer in residence for both the Chicago Symphony Orchestra and Lyric Opera, Shulamit Ran wields unprecedented influence on the local music scene. Though she's championed contemporary music, her taste is fairly conventional, veering toward the latest fads propagated by the east-coast academic establishment, and her own body of work remains rather slender. Her most impassioned and aesthetically successful composition to date, the song cycle O the Chimney, was written more than 20 years ago, at the outset of her career. Compared to it, her 1991 Pulitzer Prize-winning symphony, which receives its local debut at this week's CSO concerts, is uneven. Ran's first attempt at composing for a large modern orchestra, it expresses her preoccupation with the inevitable flow of time, and its uneasy mix of thematic elaborations showcases both sides of her musical nature--the sensual incantatory siren and the formal neoexpressionist pedant. The textures and colors are seductively fascinating at times, but this music, at least upon a first hearing, comes across as a safe albeit elegantly designed formal exercise--exactly the kind that appeals to prize committees. Also on the program are Tchaikovsky's delirious Symphony no. 5 and Rimsky-Korsakov's Fantasia on Two Russian Themes (featuring violinist Albert Igolnikov in solo turns). Daniel Barenboim conducts. A preconcert conversation on Friday starts at 12:30 PM. Saturday's concert is followed by a discussion. Friday, 1:30 PM, and Saturday, 8 PM, Orchestra Hall, 220 S. Michigan; 435-6666.