Rundgren and Hall’s professional relationship dates back nearly 50 years. Rundgren produced Daryl Hall and John Oates’ third album, 1974’s War Babies, and he and several members of his band Utopia performed on the LP. War Babies abandoned the blue-eyed soul of Hall & Oates’ first two albums in lieu of a more keyboard-heavy hard rock sound, though the duo would return to their roots on their 1975 self-titled album, which spawned the Top 10 hit “Sara Smile.� One of the great soul singers of his generation, Daryl Hall also was an inventive pop/rock songwriter, both on his own and in conjunction with his lifelong creative partner, John Oates. Hall & Oates took a long road to success, starting as a folk-rock duo at the dawn of the 1970s, then winding through soft AM pop and prog rock before striking pay dirt with the smooth soul of “Sara Smile.� “Rich Girl� gave the duo their first number one in 1977, then they entered their wilderness years as they figured out how to thread modern rock into the soul.