The STF-2 is plenty load and 'shakes the house' enough for me. Of course, if you go into higher price ranges, your furniture more with those.
At the same time, I do not want all bass drowning out the mids and high's. So I am not going to spend a boat load on a sub like that, as to me it is dumb and pointless to hear all bass.
If you want your house to shake, your floor boards to break apart, spend more and get a sub that is built just for that.
If you want good, clean, tight, deep bass that you will not be able to tell is coming from a sub(melds perfectly with speakers), then I highly recommend HSU.
