How Do I set up my subs to my stock head unit?

I have a 2008 Subaru Outback with a stock head unit. I am planing on buying one of these two subs,



http://www.amazon.com/Visonik-VPB212PK-A鈥?/a>



or



http://www.amazon.com/Dual-SBP8A-Single-鈥?/a>



Is there any easy way to hook these up without buying a new head unit? I have thought about just getting a 3.5mm male to male aux cable and a splitter, and plug one end from my ipod into my amp, via aux to rca converter, and the other through my car's aux input. I really would rather hook it up through my head unit though.



I don't believe my stock unit has any pre amp outputs.How Do I set up my subs to my stock head unit?
From what I can tell, it looks like the second one will accept a signal from your regular speaker wires, but you will probably have to disconnect the rear speakers in your car. At least you won't have to fiddle with the head unit at all.. But I always say if you are going to do something, do it right. Wait till you can get a new head unit with pre amps. It will probably have a better built in amp to power the rest of your stock speakers as well. Definitely worth it.