I wouldnt of thought the standard head unit would have a remote out! Someone please correct me if I am wrong, so instead you need to connect it to a power supply such as the cigerette lighter or similar, only
problem is you will need an inline switch to turn it off so it wont be on all the time!
Another thought actually connect it to the ignition power cable on the back of the HU, this will ensure the amp goes off with the ignition!