Just purchased and installed a new radio in my '87 740. The radio I purchased from Crutchfield's came with a wiring harness and all of that matched up perfectly except the automatic antenna connection after completely removing the amp and the original radio. Now when I turn the new radio on, I have very little volume and everything that I hear is high pitched. I wired a 6x9 directly to the radio and it sounded great! Any ideas why neither the front or rear speaker have a decent sound. I checked all of the connections and they are correct so it shouldn't be a phasing problem. It there a special ground for the speakers? What am I missing? I don't which sounds better, the new radio or my wife telling me I don't know what I'm doing.