RICHARD MIX, bass, appears with nearly a dozen Bay Area opera companies singing a repertoire that embraces Wagner and Monteverdi as well as Scelsi and Stockhausen.  A former cellist, he made his singing debut as Truelove in Berkeley Contemporary Opera’s 1992 production of The Rake’s Progress and went on to the Darmstäter Sommerferienkurse für neue Musik, to which he was reinvited with the Patenring Award in 1994 and again in 1996.  West coast premieres range from Arthur in Maxwell Davis’ The Lighthouse and the title role in Stockhausen’s Luzifer’s Traum to such recent rediscoveries as C.P.E. Bach’s Matthäus-Passion and works by Buxtehude’s colleague Heinrich Pagendarm.