Advice on my home PA system?

I have 4 15" Optimus Public Address speakers. I am currently powering only 2 of them with 2 Optimus 250 watt stereo Public Address amplifiers in a 350 watt bridged fashion. I do plan on powering the other 2 with 2 more of the same amplifiers.

My question is, while it is plenty of sound for my needs and my liking, I am not getting the bass response I want. (It "pounds" obviously, but still) I run my EQ with a flat spectrum _only_ cutting frequencies I do not desire, never adding frequencies. This allows the speakers to be driven to louder volumes, hence providing accurate audio reproduction even further. It does this due to the fact that I'm not shoving a fat signal into the inputs or trying to emulated audio tones with any sort of pre-amp. Well, I need a sub, or a pair of subs to provide extra bass (precisesly what they're for). If you are going to suggest some speakers to handle the highs, don't, I don't need that. I just need a tad extra bass, and am curious to know what size / power handling for a sub, and 1 or 2?

I am getting excellent sound due to the fact that I am "modularizing" my stereo (a speaker for every tone, hence each one can push harder).

1. This is a personal, home, PA system for a cd player only.
2. Everything being used was not discussed.
3. Everything of importance, was discussed.
4. PA knolwedge / pointers welcomed.

Any sub recommendations, or links are welcomed.

>a speaker for every tone

if that's the case, there isn't much you can do without specifically boosting the bass frequencies. perhaps use a different output source for those frequencies you'd want to increase resonance for, or cut all of the other frequencies, with only those you'd like to hear more of remaining... without pegging the bass you want to come through, i can see no other option.

>for a cd player only.

so much for a single cd? :p