Active Sub Woofer CAR AMPLIFIERS: What Amplifier Specs Should I Use With My JBL GTO Dual Sub-woofer Bandpass.?

CAR AMPLIFIERS: What amplifier specs should I use with my JBL GTO dual sub-woofer bandpass.? - active sub woofer

http://i710.photobucket.com/albums/ww109 ...
- This is how it looks

People also told me that I will need a separate amplifier to separate them. Is this really necessary?

In my capacity building of their system.

Here are the specifications of my sound system
Head of Unit: 7 "inch DVD JVC - KW-AVX820
Separate: Cadence six inches, with crossover and tweeter
Coaxial: Coaxial Kicker

I need details, what is my subwoofer necessary? Do I need a separate amplifier? If so, what kind? What brand do you recommend for sound quality.

Thank you!