I recently installed a new head unit (Atoto F7) and after it was put in I was getting a hissing noise coming from my speakers(I assume from having 2 amplifiers now) my whole sound system sounded a lot better than the stock head unit and my subwoofer had a lot more bass. I put rca’s on the positive and negative wires for the front right, front left, rear right, and rear left as I just had them hooked up the the harness before. Installing the rca’s got rid of the hissing noise but now my system seems to have barely any bass and the subwoofer is only noticeable on certain songs. I’m looking to have my subwoofer sound the same as it did before the rcas were installed but I don’t want that hiss. Any help would be appreciated.