In their 30 years together, the Kronos Quartet have single-handedly maintained the string quartet's cultural relevance. The San Francisco ensemble's dossier of past collaborations gives some sense of the breadth of their success — besides performing commissioned compositions by major modern composers like Steve Reich, Terry Riley, and Philip Glass, they've disregarded genre lines by working with Tom Waits, Nelly Furtado, Nine Inch Nails, and yodeling legend Don Walser. They'll surely be in a playful mood for this special, family-friendly Saturday matinee.