Complex sentence: Magnum moved to San Francisco in 1999, with his wife Heidi Holstrom, and opened Ensuite Studios in 2001 as a cutting-edge recording studio which primarily recorded and produced dance music.
Split into simpler sentences: Magnum moved to San Francisco in 1999, with his wife Heidi Holstrom. It was there that he opened Ensuite Studios in 2001, a cutting-edge recording studio which primarily records and produces dance music.