Main Source was an innovative, acclaimed Toronto and New York-based hip hop group comprising Toronto natives Sir Scratch, K-Cut, and Queens native Large Professor. Later, Mikey D (also a Queens native) replaced Large Professor.

Their first album, Breaking Atoms, featured conscious MC tracks such as "Looking at the Front Door" and "A Friendly Game of Baseball" and "Watch Roger Do His Thing" as well as the first on-record appearance of Nas on "Live at the Barbeque", which also featured Joe Fatal and Akinyele. Because of business differences, the group broke up before their second album, tentatively entitled The Science could be released. However, Sir Scratch and K-Cut released a second album under the Main Source name, entitled Fuck What You Think, with new recruit Mikey D on vocals; however, the album was shelved due to inner conflicts between the record label and group management. Singer Madonna sampled the bassline from "What You Need", on Fuck What You Think, in the song "Human Nature" for her 1994 album, Bedtime Stories.

Large Professor has gone on to be an instrumental producer for hip hop stars such as Eric B. & Rakim, Pete Rock and CL Smooth, Nas, and Diamond D. He has released a Solo LP entitled First Class, and his shelved The LP has been widely bootlegged.

K-Cut also produced for a wide range of hip hop artists including Big Pun, Maestro Fresh-Wes, Fu-Schnickens, Queen Latifah and even NBA star Shaquille O'Neal. He also mentored another Toronto-based producer named Watts.

Large Professor makes a reference to his falling out with Sir Scratch and K-Cut on A Tribe Called Quest's third album Midnight Marauders. On the track "Keep It Rollin'" he says, "I'm Uptown chillin, takin in this grand master Vic blend from the projects, the PJ's, fuck them two DJ's".

Mikey D currently works with Hush Hip Hop Tours as a celebrity tour guide for its Queens tour.