I have a single JBL GTO1214D 12" sub in a box in my trunk. It's powered by a JBL GTO3501 amp. Recently the sub seemed to be shorting out and would work and then stop. If I push on the sub, it will start working again and the audio place said it was going out (I think he said the voice coils were hanging up.). Before I go out and spend $140 on another identical sub, I was wondering if there would be any better sub options around the same price.