Ok, I just uninstalled my Bass knob (PRC1 is the model) which connected to the amp and to the RCA inputs of my HU. Now, for some reason the sound has changed. Not only can the subs get a little louder but the overall sound is different. I can't figure out why it is doing this. Also, it sounds like some frequencies are being played coming out of the woofers that I have never heard out of them such as the low end of peoples voices in a couple songs. The LPF/HPF of the HU and amp are still the same. I will be putting in my new amp and new bass knob tomorrow but what caused those changes?