Belder founded an ensemble, Musica Amphion, for playing mostly Baroque music. They recorded the complete works by Arcangelo Corelli, and the complete Tafelmusik by Georg Philipp Telemann in 2004. They then began a project with the label Etcetera Bach in Context, combining Bach's vocal works and organ compositions focused on a theme. The fifth recording, with organist and the Gesualdo Consort, combines the Organ Sonata in E-flat major, BWV 525, the funeral cantata Actus Tragicus, BWV 106, the motet , the chorale prelude on "", BWV 654, and the cantate .
