Right, I've finally got round to grounding the wires as per Lexx's thread, all parts bought from incartec too. However the HU now comes on, but no sound, even connecting the RCA cables.
I know the speakers etc work as I've pulled out the Kenwood double din HU that was in there prior. The steering remotes work too, power gets saved, just no sound. Really can't figure it out, I never been this baffled with car audio till I had come across the Z!
Any ideas? Gonna try again over the weekend