DaMrWolf

So I've been looking all over the interwebs for how to replace my head-unit. Seems pretty simple. However I am seeing everywhere that Subaru likes to add their own sound system sometimes to their cars... I have a '10 GT I see on the Speaker grills the HK logo and I have a subwoofer in the back window. No navagation/xmradio/bluetooth(kind of only for phone connect). How can I find out if it has its own amp/ where can I find this said amp under the passanger seat?