Common Ground

[b19upj]

I am going to install a double din head unit into my 2001 986, but i have a wiring question.
I was expecting to see 2 connectors at the back of my Beck head unit, which i would match up the correct wires from the wire diagrams i have,
BUT on take out my Becker unit i have only 1 connector (power/switched power/antenna control/ground etc) and a yellow connector.
This yellow connector has a +LR/RR/LF/RF, a common audio ground ad a 12v switched power.
Where do these get attached to on my new units ISO?
Do i split the common ground 4 times to make it - LR/RR/LF/RF?
Why are these speakers switched?
What do i do with the 12v switched wire from this connector? I'll be using a 12v switched wire from the first connector already.

TIA