The 25th Anniversary Season expands to five weeks, welcoming back early festival friends. Eugene Drucker, Roberta Cooper, and Paul Hersh perform Beethoven’s “Archduke Trio,” while Hersh and original 1981 musicians reunite for Schubert’s “Trout” Quintet. Guitarist Eliot Fisk performs works by Bach and Paganini and joins conductor David Wroe for a Castelnuovo-Tedesco concerto and Copland’s Appalachian Spring. Additional highlights include the world premiere of Three Chorale Preludes by La Fenice and Andres Cardenes performing Vieuxtemps. David Zinman returns to conduct Schubert’s Symphony No. 4, with Diane Walsh as soloist in Mozart’s Piano Concerto No. 24. Following an evening of Mozart sonatas with Natalie Zhu, violinist Hilary Hahn concludes the season with Prokofiev’s Violin Concerto No. 1, conducted by Peter Bay.