I got a JL Audio 4 Channel Amp 75X4 and connected two Diamond M360L 6.5" speakers up front and 150W going to the sub. I left the rears connected to factory unit out, and connected a 12" Diamond Audio Sub. The sound still sounds drowned out and not very crisp as it does at the stereo shop display using a headunit there. Do I need to replace the head unit? I really like the OEM look. I am clueless as to what I am doing wrong, I got high quality components, or so I thought....

Let me Know what you guys think.

 

I used different components, but basically the same. had 150w to the sub in the stock location, but it really didn't sound that great and had no punch. Just put in an aftermarket Clarion and it sounds worlds better. I can actually feel the bass through the seatback now!