The premise is simple; great vocal talents trade verses with a true master on his home turf to see who wins. In the end, everyone does, as Bennett and his swinging orchestra prove to be welcoming hosts, drawing coy warmth from Amy Winehouse (“Body and Soul”) and delicacy from Mariah Carey (“When Do the Bells Ring for Me”). He also caused such a flurry of palpable sparks with Lady Gaga (“The Lady Is a Tramp”) that the two went off to record another album together.