He made his mark in opera as three times musical director of La Scala, Milan, 1898-1903, 1906-1908, and 1921-1929, and subsequently as conductor 1937-1954 of the NBC Symphony Orchestra which was established for him by NBC (National Broadcasting Company) Radio. His wide=ranging repertoire included Debussy and Respighi, and he imparted an Italianate simplicity to Mozart and Beethoven when exaggerated solemnity was the trend in Germany.