4Voice (aka 4 Voice) is the name of Pete Namlook & Maik Maurice Diehl's trance project. They have released 3 full albums and a few 12 inches under this name (see 2350.org for discography).
The early tracks like 'Music Hypnotizes' and 'Eternal Spirit' were quite influental in the early days of trance. Pete Namlook also used to put ambient tracks on the b-sides of the 4 Voice 12 inches, to bring what was his 'main' style of music out to a different audience.

4voice on Last.fm.