The SLO Symphony is top notch! They perform monthly from September to May. The Performing Arts Center is a gorgeous venue and hosts many cultural events from ballet, choirs, comedians, musicians and more!
So many events here, too many to mention by name, although you should just go find out for yourself.
Not only does Cal Poly host a wonderful symphony hall, it also regularly features top performers and concerts. Its campus has several venues for performances, all of them small and intimate, which means that you can never get a bad seat!