“In the beginning, Haydn is always difficult,” says Alina Ibragimova, violinist of the Chiaroscuro Quartet. “He’s not an easy composer to immediately know what to do with. All the quartets and individual movements have completely different characters about them, they’re in entirely different worlds.” In this and the following season, the ensemble—a leading champion of historical performance practice—will explore the musical worlds of Haydn’s Opus 20, a work that launched the development of the string quartet 250 years ago.