| remove the cap
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 over time
to maximize clean signal strength from your amp, you need to adjust the gain or input sensitivity settings. Here's how:
Set the input sensitivity controls of your amplifier to their minimum level (counter clockwise).
Put in a CD and turn the receiver's volume control up (you might have to raise the amp's gain just a bit to hear the music).
When you hear distortion, stop. Turn the volume down until it disappears. As much signal as possible is passing from the receiver to the amp. This maximizes the signal-to-noise ratio, and leaves your system less prone to engine noise problems. Keep the volume setting here.
Now turn the gain controls on the amplifier up until it's as loud as you'll play it. If you hear distortion, slightly decrease the gain settings.
Now you've optimized the amp's output with the receiver's volume set near maximum. You can turn the volume almost all the way up and not damage your speakers or amplify distortion. If you're hooking up a subwoofer, a test disc (or bass-heavy CD) is helpful for making final adjustments | 
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