add (a component or accessory) to something that did not have it when manufactured.

That's exactly what these four master musicians do to hundreds of songs from Buddy Holly, The Beatles, Paul Simon, Sting, Herbie Hancock, James Taylor, Creedence Clearwater Revival, Stevie Wonder and many, many more. The music is warm, nostalgic, upbeat, fun and jazzy and their repertoire is the definition of eclectic.