Please help me. I tried using the 4.1 setup for my carputer and I can't get it to work. I get no sound at all. I used a HP 2.8 Ghz computer and a Rockford Fosgate Punch P4004 4 channel amp. I've tested my sound card and my amp. They work fine, but they aren't working together. What else can I check? What am I missing? I definetly don't want to have to use a HU. Thanks in advance for your help.