The season expands to three weeks of concerts at Library Hall. Pianist/violinist Paul Hersh is the artist in residence. His debut is in Beethoven’s Diabelli Variations. He performs with his son Stefan Hersh on violin in Brahms’ Sonata No. 1 in G Minor and plays piano in Bach’s Brandenburg Concerto No. 5 at Brook Farm. Frank Weinstock is the pianist in Schubert’s Trout Quintet for piano and strings: Michael Levin, violin; Marilyn Smith, viola; Lindsay Groves, cello; and Edward Castilano, bass.