ased in San Francisco, the Del Sol String Quartet is asserting itself as a leader in Bay Area new-music performance. This ensemble commissions new music from composers and showcases those and other new works in relevant, responsive and deeply passionate performances. Spark listens to the Del Sol String Quartet rehearse and is there when the quartet debuts the work of three composers -- New Zealand native Jack Body, Iranian-American composer Reza Vali and Los Angeles-based Eric Lindsay.