I assume that you have played with the 25 and 50Hz level controls on the Summits. Once placed right, broken in and dialed in they should be sufficient by themselves. A pair of Depths or Descents could take a little stress off of teh Summit woofers but the 4x1000 watt amplifiers shouldnt need any help. Heck, borrow a good sub and see if it is to your liking.
Good luck!
Good luck!