Thanks for the quick response. There definitely isn't an amp where I expected to find one, behind the removable panel on the left in the trunk. Also, when I have the head unit turned up a bit, the display fades in time with the bass so I'm pretty sure its direct driving the speakers.
I might order another pair of the 10c2's for the back anyhow. Even if they don't get full range, I'm sure they would sound heaps better than the stock items.
Appreciate any further info out there re integrating an amp into the uk spec system.