Nope, its not that. I've experimented with different sources, preamps, cables etc. It's definitely a characteristic of the speakers. I'm not the only one to hear it, or the only owner/listener to comment on it remember.
My theory is that the Horn/Tweeter is padded down that far, the the bass driver is coming up into the mid-bass area. That's whats giving the impression of "softness" in the bass.
Its not subtle either, it's there. Acceptable for Home Theater duties maybe, but not for a Hi-End two channel sound.
That's why I want to get to the bottom of it. They are such an awesome speaker in almost every other regard. That's what makes this so noticeable I guess !