What makes a string quartet? Few works have answered this question more radically than Haydn’s Opus 20 and Schoenberg’s Second String Quartet. While one of these composers presented a groundbreaking (re-)definition of the genre in 1772 that has shaped its long history to this day, the other, working a century and a half later, not only went beyond the limits of four string instruments but extended tonality itself. In the second program of its Schoenberg cycle, the Staatskapelle String Quartet combines these two works with Webern’s Langsamer Satz (Slow Movement), another defining score of the quartet repertoire.