Both the Monolith 10" and Hsu subs have good extended upper bass response. Essentially, they can both be used up to 300 Hz if the user wanted (I don't recommend that high of a crossover, though). However the VTF-2 is more than just a bit more powerful in mid-bass, it is about twice as powerful. It digs deeper too, since it is tuned a bit deeper. The Monolith subs have a higher build quality, no doubt, but the Hsu subs are really chasing after performance goals as cost effectively as possible, so two different design approaches.