At age ten he entered the Warsaw Conservatory of Music, where he initially studied piano and composition.
One day when the violin player for the hotel band did not come to work, he informed the bandleader that he was capable of filling in.
In 1916 he became music director of the Victor Talking Machine Company (later RCA Victor) alongside Rosario Bourdon, where likewise he (Pasternack) introduced Marian Anderson; and the Stanley Company of America, owned by Warner Brothers.
In his role at Victor and with several orchestras he made recordings and conducted programs for many famous singers and instrumentalists of the day, including Enrico Caruso, Fritz Kreisler and Jascha Heifetz.
From 1928 until his death in 1940 he conducted orchestras for NBC Radio, including a program with Nelson Eddy and The Carnation Contented Hour.