Oslo String Quartet was formed in 1991 by Geir Inge Lotsberg and Per Kristian Skalstad [no] (violins), Are Sandbakken (viola), and Øystein Sonstad (cello).
Their CD recordings of Carl Nielsen's quartets won them a 1999 "Editor's Choice" nomination in the international journal The Gramophone, which stated, "Artistically it is the finest at any price point ... totally dedicated, idiomatic performance ... full of vitality and spirit and refreshingly straightforward".
Their CD recordings include music by Edvard Grieg, David Monrad Johansen, Knut Nystedt, Klaus Egge, Fartein Valen, Johan Kvandal, Alfred Janson, Carl Nielsen, Magnar Åm, Lasse Thoresen, Ragnar Søderlind, Johan Svendsen, Jean Sibelius, Hugo Wolf, Ketil Stokkan, and Alban Berg.
The Beethoven Code project also included the making, and screening of the film Brødrene Gahl og jakten på Beethovenkoden, conceived, librettoed and directed by Sonstad, and featuring the four musicians as actors.
The film depicts the spiritual and existential fight and plight of Beethoven's four illegitimate children, who use the power of Große Fuge against the dark Tahitian forces of bratsjismen (violist).