Oh, a little update. the speaker is intermittant, most of the time it doesnt work, occasionally it does but it crackles.
So I guess i've blown the coil... oopsy
The wires are all intact the speaker end, not taken the head unit out to check the connections there but i'm 99% sure its the speaker.
Stock speakers and a lot of volume, not a good combination.
I'm ordering up some pioneer 100w 10cm speakers today, £20. they'll do for what I need.
Later on i'll get some in the doors as all 4 have blanking grills/pods, ready for some speakers.