There should be something more wrong with why you're not getting bass out of em. I have the same speakers and there's a lot of bass present, too much. Just no frequencies below 45 or 50 hz. But the bass that is there is too present and it's falsely fabricated, not a real true representation. That's the downfall of the speakers, but It's absolutely there.
Maybe you hooked em up wrong? is the output ok? Did you hook up other speakers to see if they have the same problem? Headphones give the same problem?