What a good sub to use with my Energy Take Classic 5 Pack 5.0?

[Beta Man]

Subs aren't really that dependent on the rest of the setup, except for driver size.... which some would disagree with.

I'd look at a 10" sub to mesh nicely.

I don't have much regard for Polk Subs.... but you could certainly use it, and if you are left wanting more... then make that decision.