to the battery, sorry. it will shock and then for a few seconds nothing. a little while after it will spark again. and when i play music the sub moves, but it does so with lottle to no power, i.e. you can see it move, and kind of hear it. but nothing much comes out of it.
When connecting these up to your battery, always remove the negative terminal first. Then connect your power wire to the positve terminal of the battery. Than lastly reconnect the negative terminal to the battery.
The reason it was sparking is because when you bring the power wire near the positive battery post, the current begins to flow between the terminal and the wire. The current can be seen as sparks. If you do it the way i said it wont do that.
Alright, so the batteries working. Everything else works in your car right? It's only your amp that's acting up? If your subs aren't getting much power, than the first thing to look at is the headunit and the amps. Of course make sure the subs aren't blown, but I'm assuming they aren't?
12.2v is a bit low. It should be around 12.5 or higher. Make sure the battery gets charged. As for your problem, are you saying it sparks all the time or just when you reconnect the power wire on the battery? With the car's internal components, it's suppose to cause a spark everytime you reconnect to the battery. It means there are electronics that is using up power. You mentioned about a sub moving with no sound. That is not related to battery sparking. Totally different problem. Describe what amp and subs you have. When the problem occurs exactly etc.