In 1976, he moved to New York City to become a studio musician, arranger, and producer for a wide range of well-known artists, including Aaron Neville, Aztec Camera, Brian Wilson, Carly Simon, Chaka Khan, Chromeo, Brett Eldredge, Diana Krall, Diana Ross, Donald Fagen, Eric Clapton, James Taylor, Karen Carpenter, Madonna, Michael Franks, Natalie Cole, Paul Simon, Rihanna, Steely Dan, and others.

In 1985, he played keyboards in a New-York-based group called Joe Cool with Will Lee, Jeff Mironov and Christopher Parker.

They released one album, Party Animals, on the Pony Canyon label in Japan, followed by a Japanese tour.

[1] Mounsey wrote two long-running Emmy-winning themes for the television show Guiding Light.

With Steely Dan With Donald Fagen With Paul Simon With James Taylor With Michael Franks With Art Garfunkel With Cissy Houston With Steve Khan With Diana Ross With David Spinozza With Spyro Gyra With others