Main Source was a Canadian-American East Coast hip-hop group formed in 1989, consisting of Toronto-born DJs and producers K-Cut and Sir Scratch, along with New York City natives DJ J.O.D. and record producer Large Professor, who was later replaced by Michael Deering, also known as Mikey D. The group's debut album, Breaking Atoms (1991), featured tracks such as "Looking at the Front Door", which reached Number 1 on the US Rap charts, and "Just a Friendly Game of Baseball", as well as the first on-record appearance of Nas on "Live at the Barbeque". Business differences led the band to disband before its second album, The Science, could be released, although the recorded material was eventually issued in 2023. K-Cut and Sir Scratch released the album Fuck What You Think (1994) featuring Mikey D on vocals, which included the track "Set It Off", marking the first on-record appearance of the group that later became The LOX. The album was shelved due to conflicts between Wild Pitch Records and management, but its track "What You Need" was sampled by Madonna in her song "Human Nature" (1994). The group's debut album was recognized in 2020, winning the Polaris Heritage Prize.