So I have a 2015 Honda Accord LX model with a stock stereo. I installed a 12 inch sub in a custom box with a 2000 watt mono block. I was setting my gains using a multimeter and when I played a 30 hz test tone I noticed a substantialy less value in voltage than with a 40 hz test tone. I've done my research and found out the signal from my rear speaker wire I spliced into and sent through my LOC is not a full range signal. I've read countless forums of people suggesting to Install an aftermarket head unit but I want to keep my factory one because the price to install a kit in this vehicle is almost $800. So my question is what are my other options in sending a full range signal to my subwoofer so It can play those really low 20-30hz tones. It's a 12 inch sub in a box tuned to 28 hz so It ***** not being able to get the full bass range sent to it. Thanks for any pointers I appreciate it!