Feinstein began working as deputy to Roger L. Stevens, then the Kennedy Center's chairman, in 1971. The collaboration lasted eight years, during which Feinstein assisted with programming and enthusiastically conducted the center's annual Messiah sing-alongs.
Feinstein hoped to elevate Washington to the status of New York and Paris as a major arts capital; he arranged visits by the Bolshoi, the Berlin Opera, and La Scala, among others. He was also instrumental in the planning and reconstruction in 1979 of the Kennedy Center's Terrace Theater.
According to the Post, budget deficits were a factor in Feinstein's decision to move to Washington Opera (now Washington National Opera), where he worked for the next 16 years, becoming general manager in 1980. His achievements there included arranging the debuts of such high=profile artists as conductor Daniel Barenboim and tenor Plšcido Domingo. He reportedly greatly increased the number of ticket sales. He stepped down prematurely when Domingo was appointed general director.
Feinstein was born in 1921 in Crown Heights, Brooklyn, to Russian immigrant parents and began studying the violin at the age of 10. He majored in music at the City College of New York and received a master's degree in music from Wayne State University in Detroit.
After serving in the army he was hired by impresario Sol Hurok as a junior press and publicity agent. He was pivotal in helping Hurok, with whom he worked for 25 years, introduce American audiences to the Kirov and Bolshoi ballet companies. One notable tour was Igor Moiseyev's Soviet folk-dance group, who appeared at the Metropolitan Opera House in 1958. Feinstein moved to Washington in 1971.
In retirement, Feinstein was an arts consultant and opera critic for the National Endowment for the Arts.