This unearthly, ethereal, half-heard sequence of arrangements is by the little-known composer Stefano Scodanibbio, a friend of the violinist Irvine Arditti. As a double bass player, Scodanibbio perhaps yearned for higher frequencies; much of this writing for string quartet is based on harmonics so that the music appears to float out of the stratosphere. What comes across is the composer's intense love for his material, which alternates between haunting Mexican folk songs (including the bewitching Bésame mucho), pieces originally for guitar, and dislocations of three of Bach's Art of Fugue. Totally original sounds, wonderfully realised by Quartetto Prometeo.