I just bought a brand new 10 inch alpine type x dual 4 ohm, the sub will handle between 500-1000 watts rms into 2 ohms, I have a older alpine m500 which will put out 500 watts rms into 2 ohms which I am using for the break in period, i have my gain set roughly 1/4 way up with bass boost at 6 and my lpf set at 75 which sounded great, I just recently a few days ago installed a 4 channel amp into my car for my speakers and every since then my sub seems to be sounding kinda muddy like my little amp is way to much for it.. But before it sounded perfectly fine and its not the speakers because when the sub is off there clear as day with no distortion, I do have the sub in a JL H.O box which I believe is 1.75 cubic feet, alpine recommends a high of 1.5 I believe but I had it in this box since day one when it sounded great so I don't think that is it.. I have a alpine Iva w203 head unit and the sub will start to sound muddy around 20 out of 35... Any help ????