Quoted from Collin:
Do you need a secondary amp of some sort?
No... tie it in to the bottom speaker or unhook the bottom speaker and go directly to the sub. Big improvement!
Great to see you're enjoying Pinside! Did you know Pinside is able to run thanks to donations from our visitors? Please donate to Pinside, support the site and get anext to your username to show for it! Donate to Pinside