"Demofoonte dates from the early Milan years of Christoph Willibald Gluck (1714-1787), long before the radical reform operas for which he is most famous and his break with opera seria and the librettos of Pietro Metastasio. Gluck arrived in the northern Italian city in 1737 and was mentored there by composer Giovanni Battista Sammartini. Though Sammartini primarily composed symphonies and music for the church, Milan boasted a vibrant opera scene,...