This internationally renowned all-male a cappella choir specializes in calm renditions of medieval and Renaissance music—including plainsong, Gregorian chants, and the timeless antiphony of the "Ave Maria." But that's just their foundation. Formed in San Francisco in 1978, Chanticleer comprises a dozen or so members, including a handful of heavenly high countertenors. The ensemble's heady elegance has extended, over dozens of albums, to African-American spirituals, prewar standards, and And on Earth, Peace, a 2006 mass involving five composers from as many countries. In other words, if it's sacred, they can sing it.