Audio Systems: Car System Capacitors, rockford fosgate amp, power cap

Question
My question is, why is it that before my capacitor used to read a normal voltage, and now it reads higher at 15 volts and every time i start putting the volume up my sub woofers shut down, then the amp reads overcurrent/protecting, at first I thought I had a shot amp, but now I bought a Rockford Fosgate amp and it's still doing the same problem, any ideas on what can it be?

Answer
I suspect either of these:

ONE:  A bad ground.  Make sure the ground wire to the amp is on solid metal and a tight screw/bolt holding it down.

TWO:  A short on one of the speaker lines or a shorted voice coil in one of the speakers could do this.

Try removing the speakers from the amp one at a time and see if you can get it back to normal operation (you may have to recharge the power cap).

Let me know if there is more to the story.

Hope this helps.
C