“Head-banging, bonkers” was how Richard Egarr described the music with which he and his colleagues from the Academy of Ancient Music were going to intersperse their programme of motets and psalm-settings by Monteverdi. About the composer in question – Dario Castello – absolutely nothing is known beyond his name, plus the fact that he took minor orders to free himself from the laws that bound ordinary people in 17th-century Venice. As we soon found out, his sonatas were commensurately anarchic, shifting violently in tempo and mood, and breaking all the then-reigning rules of harmony.