Picking up remote to switch on sub amplifier
 

Is there a way to pick up a remote signal to switch on amplifiers, etc. on a UK 2009 E61 with standard sound system? This car had no rear amplifier and the inadequate 4 inch full range speakers.

Currently using a unit that converts the speaker outputs to front, rear and sub line out. This unit is designed to sense when a signal is passed to it to trigger a remote, however it is laggy.

I am not sure that the head unit has a remote output. I would be grateful for any advice.

If you amp live is on an ignition live (which it should)you can take the remote wire from the live