新しい複雑性
Cassidy's music exhibits a radical approach to parametric organisation in composition, especially in his solo works, in a manner that he describes as to do with "decoupling". In works such as the "ten monophonic miniatures for pianist", he treats the sound of the pianist's fingers on the keys as a separate parameter in the music, and in this and other pieces he incorporates and integrates a wide range of extended instrumental techniques. He is concerned to explore the possibilities of fracturing between different musical parameters, and to defamiliarise aspects of traditional performance practice. Intellectual influences upon his music include the work of Roman Jakobson and that of Gilles Deleuze and Félix Guattari. His work is sometimes associated with the New Complexity.