Breen’s musical career began in earnest when he recorded a first album with the progressive group Chimo in 1970. He went on to play with other Toronto area groups including Southcote, Motherlode, and Brutus.

Early in 1978, he relocated to Montreal to join cult rock group Offenbach. After three solo albums and a number of diverse collaborations, including a 2 year stint as bassist/back vocalist with Celine Dion, Breen was delighted when longtime friend Jerry Mercer invited him to climb onboard April Wine.