Sparks

maybe you used a fuse that was overarted?
for your amp cabling, therefore not blowing when undermassive load, but instead, overheating and starting to melt stuff.
eh, just throwing ideas.
lol.

Check alternator

this happen to me a while ago, little different but similar i was driving along and smoke started coming out of my bonnet vents it smelt really like wires burning, i pulled over instantly what had happened is a few wires had falled down and was rubbing on the alternater belt i think, i moved the wires and taped them up and it hasnt done it since!

I had a similar event happen to me as well. But with no sparks. I was driving and i smelt this burning wire smell as well. I didn't even notice but the headlights slowly dimmed down and went off. The park lights and the interior lights were still on. Thats why i didn't notice anything besides the smell. I turned the headlights off and on again and they came back on again. And then they would turned off again when they felt like it. And that smell keep coming. Thats how i knew when they were off or dimmed. It turned out to be a headlight relay problem. So maybe you have a relay problem some where in your car. Once again check all wiring

I think your all wrong...
Major factor here is not the smell.
But the sparks.

Unless sparks were from wires in engine bay i doubt its anything else wire related,. ANd if it was something shorting and causing the battery to spark (remember sparks form left his battery is on the right..) then power would be interuptted.

I do agree with the grinding. Soemthing has caused something to rub together to cause sparks. Wheel area/brakes/axles.

handbrake might not be fully released?

I could imagine it being the cat as someone said previously. If the metal in the cat is heating up and coming out the back it could explain it. Just depends what side your exhaust is on. If it is this, just remember that you may need to check your tune because it might happen again.

exhaust is on the left... i started my car when i got home last night and it made some farked up grinding noise like it had no oil or something.. mainly coming from the gbox side.. then the smell started coming out again

so annoying !! ill just wait till the weekend when i get some time and try n figure it out

for anyone whos interested.. the problem was my AC had died..
cut the belt and now its fine !! will worry about it in summer

Good that its all sorted! I've had this metal wire stuff covered in tar from road works...get caught underneath the car on the exhaust before and cause sparks also!