Mozart adored the clarinet, and his clarinet concerto is probably the most beautiful ever written for the instrument, with its glorious themes, magnificent orchestration, and tender love song of a second movement. Completed two months before Mozart's death, it was written for his clarinetist friend Anton Stadler and the newly invented basset clarinet, basically a clarinet with an expanded lower range. The first movement is at times almost a double concerto for the instrument's distinct high and low registers--two personalities communicating back and forth through the single player. The soloist here, Larry Combs, principal clarinetist of the CSO since 1978, has an incredibly warm and luscious sound and impeccable musicianship. His register changes are seamless, his breath control amazing, and his ability to blend with another instrument or take over the melodic line from it stunning. The Mozart may make it easier to bear the weight of the second work on the program, Shostakovich's monumental, disturbing Symphony no. 8, sometimes compared to Picasso's Guernica as one of the 20th century's supreme expressions of the horrors of war. Written during WWII, it was dedicated to the victims of Hitler and Stalin and was officially censured by the Soviet government for its "unrelieved gloom." The first movement is heavy with sorrow and pain; the third provides an almost graphic depiction of battle, with percussive outbursts and relentlessly marching violins reaching an intense climax. A sudden calm suggests something has ended, but the dark, slow-moving fourth movement suggests something else has begun--something far more sinister and haunting. Semyon Bychkov conducts. Friday 11/12, 8 PM, Orchestra Hall, Symphony Center, 220 S. Michigan, 312-294-3000 or 800-223-7114, $17-$110.