Adaptations include orchestral reductions (The Clever One by Carl Orff (17 Players), The Perfect American by Philip Glass), the creation of new stories within works (Maria de Buenos Aires), revised or new stories (Winterreise, The Fairy Queen, The Diary of Anne Frank), and new reduced stage versions (Macbeth by Ernest Bloch - 110 minute one act for 7 singers, Medea by Luigi Cherubini - 95 minute one act for 7 singers).
COT opts to present the recitatives in English while keeping the sung portions in the original Italian, a format I don't usually care for but which makes sense with a rarity never before presented in Chicago. "Silla" is a very long opera (the original production is said to have lasted six hours, including a ballet not by Mozart), and Mitisek has cut the score back considerably to a practical running time of 2 1/2 hours, with a single intermission. The omissions include three arias, much dramatically irrelevant recitative and a minor character whose one aria is given to Silla –– Chicago Tribune