The 2024 Robert Mann Chamber Music Series begins with a spotlight on the Festival’s own musicians. Dohnányi’s sextet brings together piano, string trio, clarinet, and horn, an uncommon combination which the composer uses to mischievous effect. Beethoven’s brief “Eyeglasses Duo” is so called for a friendly note between colleagues — both Beethoven and his cellist friend Nikolaus Zmeskall required spectacles — and its music is similarly conversational and good-humored. Schumann embedded some of his most aching and romantic music into his Piano Quartet, a chamber gem of contrast and delight.