This is in a basement? Concrete is not a friend of huge sounding bass. I'm currently battling this fact. I built a DIY sub recently to replace an old (crappy) DIY box I had. Let's just say when you are upstairs it sounds like the house is falling apart but downstairs, esp in the sweet spot is very underwelming. I'm just as disapointed as you sounded like in your org post.

-Ben
HT v2.0
HT v1.0