This concert offers an unusual piece: a concerto for violin, cello, and piano, performed by Festival Orchestra musicians. Few composers have tried this format, but of course Beethoven succeeded. The themes are fairly simple for Beethoven, but–then again–so is the first movement of his Moonlight Sonata, and no one complains about that. Throughout the piece, Beethoven finds elegant ways to give each instrument solo turns with the various melodies, including throughout the sunny finale. The program opens with Jessie Montgomery’s Strum, a piece that, in the composer’s words, “draws on American folk idioms and the spirit of dance and movement.”