Even when they step outside their traditional trio formation, The Chicks (formerly known as Dixie Chicks) still soar. Teaming up with Tony Bennett, they come off like Nashville's answer to The Andrews Sisters on a harmony-draped take on “Lullaby of Broadway.” But each member is just as potent on her own, as lead singer Natalie Maines demonstrates on her Americana-tinged cover of Pink Floyd's folky classic “Mother.”