depends on what the 12s are rated at...if each 12 is suppose to have 500-800 watts then depending on the way you set it up, 1000 watts is plenty. Need more details though to give an exact answer...
Okay, I don't know what type of pioneer subs you have, but I think I can help you with the amp. Most Kenwood amps are not really the power output that is written on the sticker. The 1000watts there is MAX power. The RMS on that amp is probably 800 watts @ 1ohm. Therefore it's ~400WRMS @ 2ohms and ~200WRMS @ 4ohms. Now the question is are your subs dual voice coil or single voice coil? (Do they have one set of terminals each or two) If they are dual voice (two terminals each) than you will be able to get them to 1ohm bridged load and get 800WRMS to them. If they are single coil, then you will only get 400WRMS to them. This is what I need to know: Are they Single, or Dual, and what do the subs look like. Please be as descriptive as possible.
P.S. I didn't mean to insult your intelligence if you already know what Single and Dual voice coils are.