The Xbass circuit is quite tasteful as such things go, so that with headphones that general sound good but are just a bit bass shy, the Xbass circuit can be just what the doctor ordered. The key is that the Xbass circuit focuses on low bass enhancement without drifting too high upwards into mid-bass territory.
The 3D HolographicSound circuit proved, in my experience, to be both an acquired taste and a feature whose usefulness varied greatly from recording to recording. On some tracks, for instance, flipping the 3D switch might have very little perceived impact while on other the effect could be much more dramatic. Is the 3D HolographicSound circuit a good thing? Well, “good”, in this instance is in the ear of the beholder. I found that I preferred the straight, unenhanced sound of most recordings, while not noting that on a few the 3D circuit seemed a genuine benefit. Your mileage, as they say, may vary. Try the circuit for yourself and see what you think.