dont want to be a hater but that amp is medocre at best (trash), it is not CEA-compliant which means that it has been tested and produces or exceeds the advertised RMS wattage with minimum distortion (distortion over time is the MAIN cause of speaker damage)
so he would be lucky to get half of the advertised RMS wattage and it would more than likely be distorted
here are the top CEA-compliant brands
Alpine
Bazooka
Blaupunkt
Clarion
Eclipse
Infinity
JBL
JL Audio
JVC
Kenwood
Kicker
Lightning Audio
MTX
Orion
Pioneer
Polk Audio
PPI
Rockford Fosgate
Sony
http://www.ce.org/Standards/3108.asp
If you send too much power to your sub, you risk damaging it. The cone of the speaker and the mechanical parts that make it move may break under the stress. Surprisingly, too little power can also damage your subwoofer — in fact, it's actually more common than damage caused by overpowering.
When the volume is turned up and the amp doesn't have enough power, the signal becomes distorted, or "clipped." This distorted signal can cause parts of the speaker to overheat, warp and melt. Not good!
You don't have to match speaker and amp wattages exactly. An amp with a higher output than the speaker's rating won't necessarily damage the speaker — just turn the amp down a bit if you hear distortion from the sub and don't run the speaker at extremely loud volumes for lengthy periods. Likewise, you'll be OK with a lower powered amp if you keep the volume down and don't feed a distorted signal to the sub
you will send the amp into clipping
Clipping
Clipping occurs when an amplifier is asked to deliver more current to a speaker than the amp is capable of doing. When an amplifier clips, it literally cuts off the tops and bottoms of the musical waveforms that it's trying to reproduce, thus the term. This introduces a huge amount of distortion into the output signal. Clipping can be heard as a crunching sound on musical peaks.
that causes distorted sound which will damage your subs
the amount of bass you get is determined by a few different things
--cone surface area (two will always beat one)
--RMS wattage
--box type
--frequency response
--sensitivity
go with the kickers