He was a co-founder of Flederman, one of Australia's leading Australian contemporary music ensembles.
"[2] De Haan has also been active as a member of the Australia Contemporary Music Ensemble (directed by Keith Humble) and Pipeline (with Daryl Pratt), and Ii 1986 was the subject of an interview done for the NLA Oral History Program, by Australian musicologist James Murdoch.
[3] De Haan has commissioned over 150 works by Australian composers, including Love song by Carl Vine,[4] which Vine said was "Written after a long period in which both Simone and I had been involved in the performance of a great deal of intellectually, technically and physically demanding music, it is concerned more with the purely lyrical aspects of musical performance.
He has held academic positions including Professor and Director of the Tasmanian Conservatorium of Music UTAS, the Queensland Conservatorium Griffith University[9] and was Director of the ANU School of Music in 2004.
[10] De Haan's playing features in two tracks on the 1995 album Wind Song by British trombonist Eric Klay.,[11] and in October 2016 De Haan performed alongside his long-time friend, percussionist and composer Phil Treloar in celebration of Treloar's 70th birthday.