(Photo: Birgit Gufler) At the final curtain call of the Innsbruck Early Music Festival’s splendid production of Vivaldi’s only surviving oratorio, “Judtha Triumphans,” the loudest acclamation was reserved for its conductor, Alessandro De Marchi. After 13 years as its artistic director, he is stepping down from the position. The genuine warmth the festival audience showed towards De Marchi was clearly {…}