Also what contributed to the lack of bass? The unit puts out what seems to be more than enough power judging by measurements.
In my experience, you need tons of power for good bass performance. Our hearing sensitivity is poor in that region so you need the power to "feel" the sensation of bass. And yes, you do feel it in the cups and impact of the bass.
As for what is enough, the math people use never computes for me. I generally find that you need more power than the computation of sensitivity would tell you.
Alternatively, folks listen to lower levels than I do. I have set my standard to be sufficient to cover just about anyone. I don't listen at those levels all the time but for a few minutes, it is reasonable to be able to crank up the volume and enjoy powerful bass.
Finally, this is a function of the two reference headphones I test with: the HD-650 and HE-400i. With something like AKG K92, there is great power almost regardless of what drives them.