I'm just glad that everybody still gets so excited about us,” says a grateful Daryl Hall during a few minutes of downtime at his winter home in Charleston, S.C.

Excited is an understatement for fans of Hall & Oates, the number one selling duo in music history according to the Recording Industry Association of America. At any given jukebox or karaoke joint, a mix of nostalgic Gen X-ers and retro-rimmed hipsters clap to “Private Eyes,” croon “Sara Smile” ...