no sound from subwoofers

hey you guys have been a big help thanks for your time

Did you find an answer? I am having the same problem, I have two 12" Fosgate Punch subwoofers that just quit working. I hooked up another box with a single alpine 12" to the amp and it works fine, so I assume the amp head unit and wiring is working fine. The speakers have no visual damange, I thought it was strange they both stoped working at the same time, they were in installed in a box connected in parallel. During troubleshooting I connect each speaker sepertaly, still no souond. I suppose it is possible that one went out some time ago, and I just did not notice the difference. I am not very experence with car audio, I always thought a blown speaker sounded really crappy but it still produced a sound, is it a common failure to have no sound from speakers with no visual damage?