Although it can’t lay claim to the emotional dexterity and acute social awareness of Mozart’s mature works, Lucio Silla is an ambitious piece which demands a great deal of its primarily soprano cast, taking as its theme the life of the Roman dictator Sulla, though with only the most nonchalant nod to the facts of history. It’s true that Sulla did technically resign the dictatorship a few years before his death, although sadly we can’t ascribe this (as Mozart’s opera does) to the spontaneous expansion of his soul. However, this work speaks more (to us) about the history of Mozart than the bloodied final throes of the Roman Republic. Astonishing music-making, at such luxurious length, is not an ideal first opera experience, but for seasoned Mozart listeners, it was certainly an intriguing evening.