German violinist Carolin Widmann followed her ECM debut, a recording of Schumann's violin sonatas, with this recital of 20th-century duos, a return to the new music she calls her roots. With British pianist Simon Lepper she plays four works written between 1949 and 1979 by Morton Feldman, Bernd Alois Zimmermann, Arnold Schoenberg and Iannis Xenakis. Each one explores the friction between a string instrument and a tempered keyboard, and none treats the piano as a simple accompanist.

Widmann has said that the two spent more than a year choosing the programme, looking for pieces that were strong "both emotionally and with regard to compositional complexity". Lepper is best known in Britain as a lied accompanist and chamber musician. The recording was made in October and December 2006 at the WDR Funkhaus in Cologne, as a co-production between ECM and WDR, with Harry Vogt as executive producer and Stephan Hahn as Tonmeister. Rainer Peters wrote the booklet essay.

Feldman's Spring of Chosroes (1978) takes its title from a legendary Persian carpet, and its quiet, semi-repetitive figures pass between the two players at the edge of silence. Zimmermann's sonata of 1950 is a pluralist piece with echoes of rumba, march and jazz. Schoenberg's Phantasy, op. 47 (1949), his last piece of chamber music, was conceived for violin alone, with the piano part added afterwards. Xenakis wrote Dikhthas for the 1980 Beethoven Festival in Bonn, and its title refers to a duality. The violin slides through siren-like glissandi and microtones while the piano hammers out an often aggressive part of its own.

The album won a Diapason d'Or and a place on the 1/2010 quarterly list of the Preis der deutschen Schallplattenkritik. In The Guardian, Andrew Clements wrote that Widmann made "the best case I've heard on disc for the communicative power of Schoenberg's sometimes dry and forbidding Phantasy". Nicholas Kenyon of The Observer heard the sequence as "a continuous crescendo", from Feldman's Persian-inspired slivers of sound to the explosive Xenakis, and found it exhausting but rewarding. David Kettle in The Strad noted that the recording balances the instruments as equal partners.

This is the CD edition of ECM New Series 2113, released in September 2009, nearly three years after the sessions.