These duets from Mozart, Rossini and Donizetti require versatility: Terfel sings bass as Mozart’s Figaro and baritone as Figaro’s rival, the Count. And stretches of recitative show off the stars’ acting: Terfel pompously pops his p’s as the quack in “L’elisir d’amore”; as Rosina, Bartoli greets Rossini’s barber with an unstudied laugh. Terfel’s mellow maleness (with the odd artful growl) is an ideal complement to Bartoli’s breathy purity (with the odd artful snarl). Sure, they’re a couple of hams. But this disc is serious fun.