There's a new ensemble in town, focusing on the chamber music sound. The Chamber Orchestra of Louisville, founded and led by Gabe Lefkowitz, makes its debut this Sunday with Mozart, Vivaldi, and Tchaikovsky with an all-string cast of fifteen players. Lefkowitz will conduct the orchestra, but also lead from the violin as soloist in the "Autumn" concerto by Vivaldi. He played Handel with keyboardist Kirk Rich, himself a recent arrival to Louisville to lead music at St. Francis in the Fields Episcopal (where Sunday's concert takes place).