Hello I have a 2001 307 2 door 2.0 hdi 90HP it is my first car and the person previous installed an aftermarket stero, only two speakers work and the radio doesn't work well. Found the old cassete player and put that in yet I found it had this socket which I did not have the connector for (sorry for sounding thick) and it looks like this, is this the connector for the rear and tweeter speakers? and if it isn't what is it for