He sang in world premieres such as Capriccio in 1942, Hindemith's Die Harmonie der Welt in 1957, and Ján Cikker's Das Spiel von Liebe und Tod [cs] in 1969.
[3] On 1 August 1969, Klarwein performed as Timoleon in the premiere of Ján Cikker's Das Spiel von Liebe und Tod (Hra o láske a smrti).
Arabella was recorded, with Ursuleac in the title role, Hans Reinmar [de] as Mandyka, and conducted by Clemens Krauss.
[4] Klarwein participated in Salzburg, in the role of Merkur, in the dress rehearsal for the world premiere of Die Liebe der Danae by Strauss, which had to be postponed.
[1] The performance, with Martha Mödl as Klytämnestra, Anny Konetzni in the title role, and Hans Braun as Orest, and conducted by Dimitri Mitropoulos, was recorded.