Looking at the specs for the Energy, it just can't play low enough to give you the effects that you are going to FEEL more than hear. Now granted, specs aren't everything, but if those that are reported (33-150 Hz, +/- 3dB) are accurate, the speaker just can't do it (though it does a lot for the price, no question!).
For something that'll really rumble while playing movies, I'd look for a sub that has a relatively flat frequency response down to 25 Hz.
The other thing to do just to be certain before you return your sub is to do the
subwoofer crawl to be sure you have the sub in the best location in the room, which is ultra-important no matter which subwoofer you're using.
Jason
