Christensen is currently known for mastering, producing, and mixing music in the genres of rock, pop, R&B, classical, and hip hop.

Christensen has also mastered over thirty Billboard chart top ten hits, and has been involved with 50 projects that have been awarded platinum or gold status by the RIAA.

[6] He spent three years[5] living in London in the early 1990s,[5] producing independent albums[5] and touring with bands such as The Waterboys and The Clash.

[5] While at Soundtrack City, he signed another record deal based on a self-produced demo, and ended up working on tours for bands such as Radiohead, The Wallflowers and The Gin Blossoms.

Also in the 1990s he did session work as a singer, guitarist, and songwriter,[3] singing backup on several projects by Kevin Salem of Roadrunner Records and co-writing material with Ivan Neville.

In 1996[7] Christensen founded[5] Engine Room Audio (ERA) in lower Manhattan, originally constructing the studio in his loft apartment to master and record local bands.

The New York City-based band Porter Block soon joined the roster, with Christensen again mastering their debut album.

While Christensen worked on many of Engine Room's releases at that time, he also continued to master material for artists on other labels such as Babygrande.

In early 2012 Christensen mastered the first single off Trey Songz' album Chapter V, titled "Heart Attack," which was produced by Benny Blanco and Rico Love.

[8] Around that time he mastered a track for Pauly D on G-Note Records as well,[8] and he worked with the Italian rap group Club Dogo in June 2012.

In the United States, the remix reached number one on the Billboard Dance/Mix Show Airplay chart for the issue dated 16 August 2014 and is currently Platinum.

[2] Other recent mastering projects include Collide by Boyz II Men and Game Changer by Johnny Gill.