Chus + Ceballos, the A-list DJ/production duo from Madrid, Spain, dropped a set at Royale Thursday night as strong and imaginative as any I've seen them do in Boston. Beginning precisely at midnight, Chus Esteban and Pablo Ceballos laid down a train-track choogle as classic in tone and progressions as those of 1950s R&B - and as up-to-date in surface textures as an Instagram.