[citation needed] After graduation from Eastman, he was a member of the Houston Opera Studio for three years, appearing in mainstage productions of Peter Grimes, Der fliegende Holländer, Eugene Onegin,[2] La traviata, Fidelio, and Trouble in Tahiti.
[3] Shortly thereafter, he joined the ensemble, which performed Leonard Bernstein's A Quiet Place at the Kennedy Center, La Scala, and Vienna Staatsoper, before recording the opera for Deutsche Grammophon.
Subsequently, Mr. Thomsen appeared in roles such as Henry Morosus in Die Schweigsame Frau, the Steuermann in Der fliegende Holländer, in Strauss's Friedenstag and Feuersnot.
In February 2000 he also portrayed Miguel Morales in the world premiere concert and recording session for Daren Hagen's Bandanna.
He made his Opéra de Nantes debut as Belmonte in Die Entführung aus dem Serail and returned in a later season as Count Almaviva in Il Barbiere di Siviglia.