David Hassinger was a sound engineer at RCA Studios in Los Angeles.
From November 1964 until August 1966 he was the engineer for the Rolling Stones, working on all albums the band recorded in that period. During 1964 he served as "audio consultant" for the landmark concert film The T.A.M.I. Show.
Hassinger discovered, signed and managed the Electric Prunes, engineering all their recordings from their second single and first hit until their breakup in the early 1970s.
In 1969, Hassinger purchased the Moonglow Records building in Hollywood and renamed it the Sound Factory. The Sound Factory went on to become one of the most popular recording studios in Hollywood.
Other artists he worked with included Jefferson Airplane, the Monkees, Love, Crosby Stills Nash and Young, the Grateful Dead, the Jackson 5, Leo Kottke, Seals and Crofts, the Blackbyrds, Sweetwater, and George Strait.