Complex sentence: In 1972, Ferro joined the faculty of the Juilliard School, a post he held until his retirement as "vocal faculty emeritus" in 2006, although he has continued to give master classes there.
Split into simpler sentences: In 1972, Ferro joined the faculty of the Juilliard School, a post he held until his retirement as "vocal faculty emeritus" in 2006. Since then he has continued to give master classes there.