It does sound like you didn't hook up the remote wire on your Amp. It's the wire that tells the Amp to turn on and off. You don't want to go with an antenna wire. It's designed for operating a power antenna and if you hook your remote wire on the Amp to that, the Amp will only turn on while your using the radio. Meaning, you won't get sound when you play CDs. You can use an Acc line in your car. This would turn the Amp on and off with the car. The only problem would be the "thump" you're most likely going to get. This is probably your only option because I would guess that your factory HU doesn't have an Amp remote line. What I would do in this situation is use a switch. That way you can manually turn the amp on and off. This would avoid the loud "thump".