HK Subwoofers Stopped Working?

[RobC2]

I have been playing with the settings for my HK, first getting a baseline according to some guides here and then adjusting to my liking. Somewhere along the way, it seems that I lost any type of bass without bumping it up a lot in settings and playing bass heavy music. I am not positive, but I seem to recall when I got the car, it had decent bass with everything flat. I have tried putting my hand over the subs under the seats and I don't really feel anything. It is hard to tell though with so many different speakers playing. I have also tried XM, iPhone, and CD sources and same story. Any way to check without pulling the seats out? Does the bass just suck in this car and I didn't notice it before?