Welcome, shoppers!" Todd Rundgren said with a cackle, greeting the crowd two days after Christmas at the Blender Theater in New York. "Tonight's special is" — he paused for a half-second — "in your face!" It was apt warning. Fronting a quintet including his former Utopia bandmate Kasim Sulton, Rundgren jumped into a half-hour of vintage atomic pop — including his 1968 Nazz single "Open My Eyes" and the heavy-Seventies grenades "Love in Action" and "Black Maria" — then...