Sometimes spelled Cziak. Dramatic singer and composer, who was born at Mirowitz, Bohemia. He was a pupil of Freiberth in Vienna and studied composition in Prague with Anton Laube. He became chapelmaster to Prince Karolath in 1780, then sang in Vienna, Prague, Salzburg, Gratz and Munich, where he was pensioned in 1805. His voice was a tenor of great flexibility and power. He sang the roles of Tamino, Count Almaviva in Barber of Seville, and other parts. He was on intimate terms with Mozart, and it is said that Mozart often used to touch up Schack's scores for him. For him, Mozart wrote the role of Tamino. Schack was a good musician and a fine flute-player, and was beside extremely well educated. He composed several operas for Schikaneder's theatre; and others with Gerl, which were published between 1789 and 1793, among them Una cosa rara; Die Wiener Zeitung; and Don Quixote, an operetta, produced in 1792. His other works include six masses; three oratorios; two funeral cantatas; two requiems; graduals and offertorios.