Produced by group members Robbie Chater and Darren Seltmann, "Since I Left You" utilizes numerous samples of other artists' material.

A surrealistic music video for the song was directed by Rob Leggatt and Leigh Marling, and depicts two miners who find a mysterious passage into a dance studio.

[1] Production was handled by group members Robbie Chater and Darren Seltmann, who composed the album's songs by sampling music from vinyl records and manipulating them using Yamaha Promix 01 and Akai S2000 samplers.

[7] The "Everyday" sample was the final element of "Since I Left You" to be added by Chater and Seltmann, and the former stated that its addition was a moment when they "really succeeded in writing a pop song.

[6] Other sample sources include Rose Royce's "Daddy Rich", Tony Mottola's "Anema e core" and "By the Time I Get to Phoenix", the Duprees' "The Sky's the Limit", Lamont Dozier's "Take Off Your Make-Up" and Klaus Wunderlich's "Let's Do the Latin Hustle".

[11] The CD single contained the non-album track "Everyday" and a remix by English electronic musician Andy Votel of a previously released B-side, "Thank You Caroline".

[11] Remixes of "Since I Left You" by alternative music band Stereolab and producers Prince Paul and Cornelius were created for the single's American release.

"[19] Allmusic's MacKenzie Wilson also spoke favourably of "Since I Left You", remarking that it "leaves listeners spellbound and in a summer dreamscape of lushness and simplicity.

[32][33][34][35] The Avalanches had originally envisioned a video concept involving synchronized swimmers on an ocean cruise liner, but their record company rejected it.