Husband and wife duo The Captain & Tennille are best known for their sappy love songs from the '70s. But Grammy Award-winning singer-songwriterRosanne Cash says they actually had some real musical chops --- or at least one of them did."Toni is the one who obsesses me," she says. "She sounds like a cross between Dusty Springfield and Dionne Warwick."Cash argues for the allure of the incongruous duo and defends her love for this maligned Billboard number-one single.