Led by sisters Ann and Nancy Wilson, Heart struck a crucial blow for feminisim in the male-dominated world of '70s rock. They could switch from powerful, Zeppelin-like grandeur to gorgeous acoustic ballads in the blink of an eye and turned out a stream of radio staples. By the '80s, they were churning out slick pop, but the sisters re-emerged in the '90s in stripped-down acoustic duo format as the Lovemongers.