I have a 97 Grand Carvan SE that has the infinity stereo system. The factory cd went on it so I had a new sony cd/mp3 player put in. The problem is that it doesnt sound near as good as the original deck. It is a high powered Sony deck but sounds "tinny" little base. Are there factory amps in this vehicle? If so where are they located. I think the dude who installed it failed to hook them up. -THanks!