Basically its just that you don't have enough power to run the subs and you are pushing them too hard. If they are 2 ohm dvc's then you should only be able to get a 2 ohm or 8 ohm or .5 ohm load. I don't think you are able to get a 4 ohm final load. You have two speakers right? Do you have all terminals on the speakers hooked up?
this shows they dvc subs can be hooked up. I think there is one more way to get an 8 ohm final load they dont' show.
http://www.jlaudio.com/tutorials/wiring/index.html

To keep it form clipping you can just turn the gain down on the sub channel and should be fine.