first a sound wave on an scope looks like the ones your used to seeing
http://www.google.com/imgres?imgurl...a:en-US:official&channel=s&ndsp=20&tbs=isch:1
now, when you clip, instead of having a nice curve the hills and valleys get flattened.
like this
http://i81.photobucket.com/albums/j230/sparky3489/Clipping.jpg
this is were having things matched is good. you get clipping most from asking your amp to work to hard. as the sign wave amplitude gets bigger it can move outside of the control of the amp's solid state electronics and start to clip.
now if you have the subs turned down. and you crank the HU vol up. you can clipp that too. and now your sending a clipped signal to the amp and its just repeating it.
if your wondering how this is bad?????
your sub wants to go back and forth and vibrate. when a speakers works it creates a electromagnetic field in the windings that pushes against the true magnet. and moves back and forth. but the excited coil doesnt stay on. or the sub would just push out and stay out. but rather off on off on on on off. as it needs to to play "music". so think of the clipped signal as the movement of your sub cone. when its clipped the cone pushes out and stays there for 1/10th of a sec then comes back down and plays some then the next big bass hits and it stays pushed out again ect ect.
this casues a few things to happen
one: the music can suck if its really bad, because the sub isnt free moving.
two: coil is holding the cone out the "power" is staying on. and building up heat.
three: your really kinda slamming the sub all the way out going past were its supposed to go.
welll yea hope this helps