As a general rule, principal positions in major symphony orchestras are not filled by complete unknowns. A musician hoping to become principal viola of the St. Louis Symphony Orchestra, for instance, would generally need to have a) some experience as a principal in a lesser orchestra, or b) a position as a sub-principal in a comparable orchestra in order to have a realistic shot at winning. All of which makes the story of Shannon Farrell not only rare, but downright inspiring to other musicians on the audition circuit. Farrell, the 7th chair section violist of the Louisville Symphony, marched into St. Louis this month hoping to sharpen her skills with a tough audition, and walked away with one of the preeminent orchestral jobs in the U.S.