Need Help With Sub and Amp Combo

If the sub is dual 2 ohm, you can wire it to 1 or 4. That amp could be bridged at 4 ohm to give you 800w according to the specs, though I doubt those numbers are accurate. I haven't used those amps before so have no idea. I personally would get a decent class D monoblock that gives you 1000w@1ohm.  A class D will also be more efficient, so less taxing on your electrical system assuming you are getting the same power from both amps.

Just looking at the fuse on that amplifier its likely only going to put down real RMS power at 4 ohms of about 400 watts RMS. That will work ok with that subwoofer if you build a large ported box or might be Ok in a very large sealed box.  I was going to model it for you but I couldn't find a Rockford Fosgate power hx2 unless you mean P2. The description in the picture is cut off at the top.