Lost Subwoofer On My Sportcross

[clossie]

I have recently replaced the head unit in my is200 sportcross with an alpine ida x101, which sounds fantastic however: I have noted that since cutting the amp out of the loop, I have lost the use of the subwoofer located in the boot of the car. Having looked at my head unit I now realise that this is because via the alpine connector block, my head unit unfortunately only has four channels. FL/FR RL/RR.

The sub woofer out is on an RCA connector!!

So...my question is as follows. I was wondering whether (with some time and patience), I could retro connect my new headunit block into the old wiring loom to the amp, buy an rca cable, cut one end off and splice it into the old loom also. This I hope will get the old sub firing back up again..

Or.. does anyone know the specs of the Sub? Could I just buy an amp, rca connect my sub woofer output from the headunit to the amp, and then pick up the wires for the sub from the old loom and fire it up that way.(does anyone know which ones they are?)

Or... do I live with just the 8 speakers..(shame tho)