Hey jmai22,

I would definitely go the speaker route first. Like everyone has said, you'll get the best impact this way since the one speaker you have is messed up. Also, I would bet that the Axiom's will out-perform your Pioneer's. Also take heed to what spiffnme has said. Make sure you pick the right speaker as even within Axiom, their speakers will have different characteristics.

The next step should be your receiver (and center speaker if you can), followed by your surrounds and then the sub.

Aeromos