Hello, A few years ago I purchased a subwoofer from accousticvisions and an amp from parts express. I believe the sub was called a DPL12? And the amp is the 250 watt parts express amp. So far I have been very pleased with the performance of this combination. However, recently, my sub does not seem to be working correctly. In order to get any sound at all to go through it I have to crank the crossover almost all the way to 160hz. Once I crank that over I have to really turn up the volume to get anything at all. It did not used to be like this. I have tried switching the cable connecting the setup to my sony receiver, but have not had any luck with different cables. I am wondering if there is something else I can do to troubleshoot this, or if maybe my amp has just gone bad? Any help would be appreciated. Not sure if i provided enough information, so just ask if you need more. Thanks!!!