Does the ISO converter not have any speaker connections on it?

On my gfs the headunit has a multiplug that comes out the back of the headunit and goes down to the drivers footwell where there is an amplifier - and obviously the speakers are all connected to this.

Im not 100% sure where the amps are on the saphs. Mine (early 4x4) came with a graphic equaliser in the lower din pocket which the speaker wires were connected to IIRC.