[2] After moving to California, Marshall collaborated with Grisman on film music and joined his quintet.

He was a member of the David Grisman Quintet from 1985 to 1990, touring with Jerry Douglas, Béla Fleck, Tony Rice, Mark O'Connor, Stéphane Grappelli, and Darol Anger.

They founded Montreux, with Barbara Higbie and Michael Manring, and the supergroup Psychograss, with Tony Trischka and Todd Phillips.

Like Grisman, both groups played an eclectic style of music that combined classical, folk, jazz, and bluegrass.

Marshall has performed Brazilian music with the band Choro Famoso and on his second solo album, Brazil: Duets.