I think it was either one wire to the cree PCB or the capacitor I removed and replaced when fitting it. I have resoldered new wires to the + and - of the board and refitted the capacitor and it is working again.......phew......at least for now
Was panicking a little bit there.
EDIT: Please don't laugh at me (ha, ha) but I just put the Crack back "in situ" and noticed that I hadn't turned the DAC on at the wall. lol. BTW This baby is sounding really nice at the moment even if I just go direct from my laptop's 3.5mm into the Crack.