It looks like there's bass there in that graph, but really, below 27~28Hz you couldn't hear anything. Getting close to the sub, it was pumping its little heart out in the low 20s, and it wasn't bass so much as distortion. And it did stop making noise at 20Hz. Maybe a limiter in the amp, I don't know.
If you look in the archives, I posted quite extensively on my old H100, with lots of graphs and pictures.
I have a HSU VTF-3 MK2 now, in a different room. But in my new room (much bigger now), I put the H100 on top of the HSU to demo it for the person that bought it. It's a decent little sub for small or medium rooms, but it wasn't even close to the HSU. Not by a long shot. It has the same amp as the STF-1, so it's probably that kind of comparison. In a medium-large room, decent enough for some low end for music or movies, but not for serious HT or if you like a lot of bass for music. You can crank it and run it hot, but it doesn't compete with the big boys.
Really, the H100 is only good to 27~28Hz. This falls in line with the STF-1 and x-sub, both 8"ers (and the H100 and STF-1 have the exact same amp). A sub with stronger output below 30Hz, like my new sub, wouldn't have dropped off like that in that room. It just doesn't go that low.
And yes, an eq would have helped. I have bass traps and a BFD (and REW) now, if you've seen me post on numerous threads here, or in the BFD/REW area