Another commission by Dennis Russell Davies was a second series for piano, the "Etudes" for Piano (dedicated to Davies as well as the production designer Achim Freyer); the complete first set of ten Etudes has been recorded and performed by Glass himself. Bruce Brubaker and Dennis Russell Davies have each recorded the original set of six. Most of the Etudes are composed in the post-minimalist and increasingly lyrical style of the times: "Within the framework of a concise form, Glass explores possible sonorities ranging from typically Baroque passagework to Romantically tinged moods". Some of the pieces also appeared in different versions such as in the theatre music to Robert Wilson's "Persephone" (1994, commissioned by the Relache Ensemble) or "Echorus" (a version of Etude No. 2 for two violins and string orchestra, written for Edna Mitchell and Yehudi Menuhin 1995).