The Metamorphoses of Britten for Solo Flute/Alto Flute
Pan - Journal of the British Flute Society
Written for flute or alto flute. I am an alto fan, having played it a lot with a Barcus Berry pick-up in my Ben-Tovim Ensemble (amplified viola and cello, electric and classical guitar and bass guitar).
Difficulty level, roughly compared to ABRSM exam grades. 0 is beginner, 9 is advanced (beyond grade 8).