For 50 years, San Francisco’s Kronos Quartet — David Harrington (violin), Gabriela Díaz (violin), Ayane Kozasa (viola) and Paul Wiancko (cello) — has challenged and reimagined what a string quartet can be. Founded at a time when the form was largely centered on long-established Western European traditions, the Kronos Quartet has been at the forefront of revolutionizing the string quartet into a living art form that responds to the people and issues of our time.