[5] Sommer was a member of the Glenn Branca Ensemble, and played alongside Sonic Youth's Thurston Moore in the New York City punk rock band Even Worse.
Sommer had a small speaking role in Tougher Than Leather, a 1988 feature film starring Run-D.M.C., Beastie Boys and other acts from the mid-1980s New York City hip hop movement.
[6] Sommer began working with New York City–based rock band the Indecent in 2008, in collaboration with Stuart Chatwood (formerly of the Tea Party), and produced their self-released debut album, Her Screwed Up Head (2010).
In the late summer of 2010, along with Julian Raymond, he produced post-album demos for the Indecent which led to the group being signed to Warner Bros. Records.
He was also involved in the early careers of both the Beastie Boys and Kara's Flowers, producing three tracks for the latter in the summer of 2000, shortly before the group changed their name to Maroon 5.