Performing as Hauschka Germany’s Volker Bertelmann is a leading exponent of ‘prepared piano’ – a technique by which the musician interferes with an instrument’s internal workings in order to access a wider range of sounds. YouTube videos of Bertelmann clamping rubber between the strings or covering them in pingpong balls attest to how far is prepared to take the conceit. On his ninth album, there’s precious little over quirkiness, however. Working with Mum drummer Samuli Kosimen, the record fuses avant-garde electronica, post-classical tinkering, alongside sudden lurches into rag-time and jazz piano. Little here could truly be described as boundary -pushing but Bertelmann is constantly trying on new styles and the record’s inability to stand still is chief among its charms.