I am really wanting to find a small bass cab that will also serve second duty as a bi-amped sub on a 420 Watt PA (with no drums). I will run full-range speakers off one 210 watt amp, and run the sub off the other. Now if the best bass sound in the world comes from these tiny cabs with tens and twelves, then why would a person ever need a huge eighteen inch sub on the PA to reproduce the same tone? Am I wrong here, or is the 18" sub only needed for the kick drum? It seems the PA sub should be the same cab as the bass amp, which would mean tens or twelves.