Calling Fritz Hauser a drummer is like describing a hologram as "a snapshot." Technically correct, it quite misses the point. A master colorist, this Swiss percussion virtuoso layers not just rhythms but sounds, from the distant rumblings of soft-pedaled dual bass drums to the wildly expressive sparkle of widely tuned cymbals; a superlative composer, he uses his drum kit as both desk and orchestra, the place where his carefully structured pieces are both conceived and fully executed. Hauser's performances and recordings over the last decade have been confined to solo and duo contexts (he was last heard here in partnership with saxist Urs Leimgruber, in June). "I have the feeling the sound of my drums is always distorted by other instruments," he has said. "I definitely like the pure percussion sound." Along those lines, he has commissioned 11 short pieces by a wide range of modern composers--including John Cage, drummer Joey Baron, and Pauline Oliveros--and structured them into a new concert-length program that received its world premiere in New York last week; this performance will be only its second since then. If you're one of those whose eyes glaze over at the concept of a solo percussion concert, fine--stay home. That assures the rest of an odds-on chance of finding a seat. Saturday, 8 PM, Southend Musicworks, 1313 S. Wabash; 939-2848.