For his 16th CD, Henning Sieverts' 'Double Quartet' (Pirouet) reaches back over 600 years to research the history of the Bavarian Irsee Monastery in uncovering a mass written in 1614. He then wrote 15 original pieces of music (shortest 51 seconds; longest 12 minutes) for duo, quartet and octet in a similar style but expanding it into modern jazz. No overdubs.