Staged by Gustav Rudolf Sellner, conducted by Lorin Maazel, with costumes by Filippo Sanjust and performed by the six soloists with consummate vocal elegance, Cimarosa’s “Die heimliche Ehe” offers unalloyed pleasure, triggering a kind of ecstasy with its combination of delicacy and opulence and its refined humour. It brings out Cimarosa’s musical mastery – but also the visual impact of the opera.