another amp question...

I currently have a Sony 4 channel marine amp. I think it is the only marine amp Sony makes. Long story short..it didn't really drive the 12 inch JL sub I just bought--unless you listen exclusively to german techno all day.. meaning I could hear the bass on some stuff if I really cranked it.. .
I have this..
Sony:

General
Class AB
Channel Operation 4
RMS Power @ 4 Ohms 4 x 60 Watts
RMS Power @ 2 Ohms 4 x 70 Watts
Total RMS Power 280 Watts
Peak Power Output 440 Watts
Minimum Impedance Unbridged 2Ohms
High-Pass Crossover Frequency 80 - 20,000Hz
Low-Pass Crossover Frequency 80 - 20,000Hz
Signal-to-Noise Ratio 97dB
Frequency Response 20 - 20,000Hz

I was looking at this amp as a better choice to power the tower speakers(Rockford Fosgate-Power/Punch?)and the JL sub--and be ready to add components later?
Description

NEWEST MODEL!

THE ZX700.5 700 WATT RMS 5 CHANNEL AMPLIFIER IS ONE OF THE MOST AMAZING CAR AMPS. THIS ONE AMP WILL DRIVE YOUR ENTIRE SYSTEM. THE FRONT FOUR CHANNELS WILL POWER YOUR INTERIOR SPEAKERS AND GIVE THEM THE POWER TO BE LOUD AND AT THE SAME TIME HAVE AMAZING SURROUND SOUND. YOU WILL ALSO LOVE THE IMPROVED CROSSOVER FREQUENCY, WHICH WILL ENSURE THAT YOU GET THE RIGHT SOUNDS OUT OF THE RIGHT SPEAKERS.

THE CLASS D, BASS CHANNEL WILL PUMP OUT 400 WATTS OF EARTH-SHAKING BASS TO 1 OR 2 SUBS. THE BASS CHANNEL HAS A LOW-PASS CROSSOVER THAT WILL GIVE YOU THE DEEPEST AND CLEAREST BASS AVAILABLE.

KICKER IS KNOWN TO PRODUCE THE HIGHEST QUALITY CAR STEREO AMPLIFIERS. 100 WATTS OF KICKER WATTS ARE EQUIVALENT TO 300 WATTS OF AMPS MADE BY OTHER COMPANIES.

FEATURES:

* 85 watts x 4 @ 2 ohm+ 420 x 1 at 2 ohms
* 70 x 4 @ 4 ohms + 420 x 1 @ 2 ohms
* 130 x 2 @ 4 ohms + 420 x 1 @ 2 ohms
* Class D Sub channel is 2 ohm stable
* front and rear variable high-pass crossovers: 50-200 Hz @ 12 dB per octave
* variable 50-200 Hz low-pass crossover @ 12 dB per octave (subwoofer channel)
* efficient Class D sub channel
* 0-18 dB bass boost at 40 Hz
* 3, or 5 channel output
* Tri-Way capable
* dash-mountable remote bass level control
* speaker- and preamp-level inputs
* frequency response 20-20,000 Hz
* 4-way protection circuits
* Dimensions: 20" L x 2-1/8"H x 9-5/8"W

Think I should re power my sub with type of deal or another variety....I think I heard that most will favor a mono channel amp for a sub. This is not a marine amp--but will be well protected.
thanks
jg.