After coming top in his class, Sinclair started as an engineer at The Lab and eventually took over as in-house engineer from Mark Tierney.
Although Sinclair loved rock, he ended up working on and with a lot of dance music acts, mainly those associated with the Deepgrooves label. He engineered tracks for 3 The Hard Way, Urban Disturbance, Grace, Fuemana (led by Phil Fuemana), Lost Tribe, Moizna and others.
Sinclair was one of the partners who set up the Deepgrooves in-house production studio Kaiun Digital (along with label boss Kane Massey and video maker Dean Mackenzie), handling the recording side of the operation. As well as engineering for Deepgrooves, the studio was also used by other local indie labels such as Tangata and Urban Pacifica (owned by Phil Fuemana).
After Deepgrooves sold off its studio equipment in the latter part of 1998, Sinclair decided to relocate to the UK, and left the country the following year. He has since focused on film and TV sound post-production and mixing. He returned to New Zealand in 2010 and continues to work in that field.