Born in Toronto, Ontario, to Jewish Latvian immigrant parents who raised their four children to become persevering kids, Adaskin studied the violin with Alexander Chuhaldin at the Toronto Conservatory of Music. He began his career playing the violin in silent film presentations in his native city. Afterwards, he was a violinist with the Toronto Symphony Orchestra from 1923 to 1936. He married his first wife, soprano Frances James, around that time. From 1938 to 1952 he was with the Royal York Hotel trio. Adaskin attended the Music Academy of the West in 1950.