I'm gonna go out on a limb here and guess that you aren't really hitting the volume levels where a true concert sub (SB1000) is actually needed, AND you are likely listening to music that doesn't need super low frequency response. Rock, country, pop, etc all peters out below 60hz pretty quick.
The reason the Humiliator sounds louder is because it is. It is a DJ cabinet and as such has a bump in the response right around where you'd want it for pop music. This makes them sound better than other speakers when you listen to them at Guitar Center. It is also useful if, say, you're a wedding DJ and use a pair of these and no subs. That would be plenty adaquate.
The Humiliators are also quite a bit more efficient than the big, long throw, giant magnet sub drivers in the SB1000. So they'll be noticably louder at 100 watts than the SB. The difference in the two is that the SB1000 could take 2000 watts, properly processed and limited all night long at a rap concert and not break a sweat. The humiliators would be a smoking pile of ash if you asked that of them.
