If you try pushing the headphones of the UE6000 closer to your ears, would that increase the bass for you? Since I now have bent mine quite a lot and have much better clamp and seal from the headphones compared to when I got them. Almost on the uncomfortable side because I have glasses and the headphones push on the glasses.
Pushing the cups closer increases the loudness overall, including the bass. It still doesn't change the signature nor does the bass improve enough to feel like it's not rolled off.