The San Francisco Friends of Chamber Music provide a nice classical chamber series at the Legion of Honor, but their signature event has quickly become Chamber Music Day at the de Young Museum. It's seven hours of performance, discussion, discovery, wandering about, and meeting people. You won't want to miss this, because there is a huge variety of acts planned, ranging from early music (Voices of Music, Halifax and Jeffrey) to Latin (Quinteto Latino), to musical omnivore acts (Quartet San Francisco), to “world fusion” (Ultra World X-tet), to jazz (Marcus Shelby Quintet) to adventurous string quartets (Del Sol Quartet), and pretty much anything else you might be into.