I just bought a 2005 Grand Prix GT a few days ago. Long story short, the previous owner had installed a pretty nice sound system, but they had taken the aftermarket amp with them, leaving the wires exposed in the trunk and none of my speakers working. I took it to Best Buy and the guy gave me two options. Either I purchase a new amp and new wires, or just purchase the new wires and he will hook them up to the radio (which is a Sony, not sure which model). I chose the cheaper way because I was told it would sound just about the same just not as loud. So once they finish I turn it on and all of the speakers are working, but there's absolutely no bass. This is where I'm confused... previous owner had installed two Infinit subwoofers in the trunk and the stock monsoon amp in between them. Wires all seem to be running through it, so I don't understand why when I turn my subwoofer to max power, nothing changes. It's basically just treble. I'd like to get input before bringing it back to Best Buy tomorrow. Also, my auxiliary port isn't working. I've tried three different cords, nothing. Thanks!