Stop,First what ohm load stable is your amp?
Second what ohm load is your sub?

If you have a amp that is 2 ohm stable and a dual 4ohm sub then you run it in series.
If you have a 2 or 4 ohm sub and a am that can only run 4ohm mono(bridged) and 2 ohm stero then you also have some options.

If you need any real help or a walk through shoot me a pm with your phone #.