The vocalist who can hold the cavernous Met auditorium spellbound with just a pianist for backup is a rare bird indeed. In the intimacy of Salzburg’s 800-seat white-and-gold Mozarteum, Diana Damrau has been known to lock eyes with a responsive listener and forge an instantaneous bond. But as she has proven time and again since her triumphant Metropolitan Opera debut 15 years ago, her spell just as easily embraces all those wonderful people in the dark of the top gallery. A solo recital for Damrau at the Met announced for last March would have elevated her to the pantheon of just 16 colleagues the Met has ever presented in this manner. The pandemic spoiled that plan, but here she is, proudly flying the Met banner in a live broadcast from Caserta, Italy, joined by the tenor Joseph Calleja, a Golden Age throwback from the Mediterranean island republic of Malta. —M.G.