There’s a big problem trying to turn something as sprawlingly theatrical as “Angels in America” into an opera. “It isn’t enough simply to reflect what is already there, or to enhance the mood like a film score,” writes Rupert Christiansen. “Music must be the driving force, the medium of revelation. This is the hurdle at which the composer Peter Eötvös and his librettist wife Mari Mezei fall flat on their faces. Their adaptation of Angels in America, Tony Kushner’s apocalyptic epic of Aids and the spiritual turmoil of the Reagan era, condenses rather than expands the theatrical original, squeezing a gallon of drama into a pint-pot of opera.”