Simmons was born in San Francisco, California, in 1950. At the age of 9, he entered the Bay Area's musical scene and began living his dream of becoming a world-class musician. He had been taught the piano from an early age by his mother, Matty. By age 11, he was conducting the San Francisco Boys Chorus, started by Madi Bacon, of which he had been a member. Bacon gave him the early artistic freedom to assist with the chorus that would serve him and others for years. He was assistant conductor with the San Francisco Opera from 1972 to 1975, winning the Kurt Herbert Adler Award.