Bachanalia, a conductorless string orchestra founded by violinist Nina Beilina in 1988, continues its 25th season, “Silver Encores,” with a concert entitled “Jewish Voices” at Congregation Ansche Chesed. The program includes works by Johann Sebastian Bach, Dmitri Shostakovich, Steve Cohen, and George Gershwin, as well as some traditional klezmer music for solo clarinet and strings.