So happy together: Like the name MKTO, which combines the initials of singers Malcolm Kelley and Tony Oller, the duo blends genres on its bubbly breakthrough Classic. "I love pop and rap," Oller says.

Who or what is MKTO, exactly? Well, I’ll tell you this: you’ve probably heard their music on the radio before and not even realized it! MKTO is an American pop duo made up of members Malcolm Kelley ...