Polish bass Leonard Andrzej Mróz died at the age of 73 on Dec. 13 in Warsaw, Poland.   Mróz was born on Jan. 19, 1947, and studied in Warsaw. He went on to win several international competitions including the sixth Polish National Vocal Competition. S. Moniuszko in Wrocław as well as competitions in Munich, Geneva, and Amsterdam. He followed it with an {…}