Here's my setup. I have a 12v battery. The positive terminal is hooked up to a 25A fuse on 10 gauge wire. The fuse leads to a 25A switch. The switch goes to my amp power. The amp is grounded to the negative terminal on the battery. The amp has power. I have 2 16 gauge wires running to the positive and negative speaker power. for input I have an RCA to 3.5mm cable. I plugged my phone into this and I can faintly hear the audio by pressing my ear to the speaker all the way turned up. I connected a jumper wire from power to remote so the amp would turn on.
Does this sound only happen when you are using the 3.5mm to RCA connector?
This is the only way I am able to test it. So I'm not sure. It could either be a problem from the music source or the cable to the actual wiring to the speaker OR the speaker itself. Although I've tried two new speakers.