In 1949 Grossman joined the conducting staff of the newly formed
NBC Opera Theatre (NBCOT). In 1952 he took a leave of absence from that organization to further hone his conducting skills in Europe. He spent the next two years on the musical staff at the
Bavarian State Opera and working as an associate conductor of the
Munich Philharmonic. He returned to the NBCOT in 1954 when he was appointed the company's new associate conductor, and in 1956 he was promoted to conductor at the NBCOT. While working for the NBCOT, Grossman joined the conducting staff of the
New York City Opera (NYCO) in 1955. His first opera with the company was a production of
Georges Bizet's
Carmen with
Gloria Lane as the title heroine. He conducted periodically at the NYCO over the next several years, leading performances of mainly contemporary works like
The Medium and
The Triumph of St. Joan. In 1956 a successful guest conducting job with the
Baltimore Symphony Orchestra led to further contracts with that orchestra, and ultimately to his appointment as associate conductor in 1959. after which he served as associate conductor of the
Pittsburgh Symphony Orchestra under conductor
William Steinberg in 1962-1963. In 1958 Grossman conducted a production of Menotti's
The Consul at the
New Orleans Opera. That same year he worked for the first time on
Broadway as the music director of Menotti's
Maria Golovin; a work which he later conducted at the NYCO in 1959. He went on to conduct for several more original Broadway productions, including
The Roar of the Greasepaint – The Smell of the Crowd (1965),
Drat! The Cat! (1965),
Walking Happy (1966–1967), and
Cry for Us All (1970). His last conducting job on Broadway was for the 1972 musical
Ambassador. Grossman was also a frequent conductor at the
San Francisco Opera (SFO) during the 1960s. He first conducted for the SFO in 1964, leading a production of
Carlisle Floyd's
Susannah starring
Lee Venora in the title role and
Richard Cassilly as Sam. Other operas he conducted at the SFO were
Madama Butterfly (1965),
The Crucible (1965),
Carry Nation (1966),
The Turn of the Screw (1966),
The Magic Flute (1967),
Manon Lescaut (1967),
Cavalleria Rusticana (1967),
Pagliacci (1967), and
The Tales of Hoffmann (1967). He also served as the Music Director of SFO's Western Opera Theater from 1966–1968. The couple notably collaborated on translating Puccini's
Gianni Schicchi into the English language; a translation which has been widely used (including by the
Metropolitan Opera) and is included in the published score by
Ricordi. In 2009, Grossman married former friend and opera singer Sylvia B. Davis (1935-2022) in a ceremony at West Gilgo Beach, New York. Davis died in 2022 in Northridge, California at the age of 87. Grossman died in 2010 at the age of 83 in
West Gilgo Beach, New York. The cause was
kidney failure. ==Recordings==