It's actually very easy to get great sound from a sub or two, so don't pay much attention to anybody saying otherwise. Use subs that take the signal from the amp, like RELs or Vandys , and simply move the sub around and adjust the level. Not as head scratchingly difficult as many imply. Note that a good sub (I have 2 perfect "previously owned" RELs bought cheap) allows control over the bass simply by phase and level adjustments on the sub, and DSP in most cases is unnecessary and just adds electronic junk (and more cables to get in the way) to the signal...less is more, simple is better. A "full range" tower speaker generally doesn't allow the flexibility of bass control, and obviously doesn't allow for bass speaker placement free of the main speakers.
