FIRST OFF. . .

Dave Brubeck and his quartet will leave on Monday for a 16-day tour of the Soviet Union, the United States Information Agency announced on Wednesday. The jazz pianist--accompanied by Bill Smith, clarinet, his son Chris Brubeck on trombone and bass, and Randy Jones on drums--will play five concerts in Moscow from next Thursday through March 30, three in Estonia (April 2-4) and five in Leningrad (April 6-10).