I installed an Alpine CDE-100 headunit in my 2004 Impala and the stereo works fine with CDs and iPod but the am/fm radio quality is terrible. When installing this headunit I was forced to buy an am/fm adapter plug to go from my antenna to the back of the headunit. Could it be that the adapter is bad? It has sounded terrible for a couple months ever since I put it in just never really felt like trying to fix it. Thanks for any help!