Without wishing to get involved, I think the point a few of the other posters were trying to make is that the Nuraphone "personalises" the EQ for each person - therefore, if you were suffering a lack of sensitivity or hearing loss in the mids (for instance), the Nuraphone EQ would compensate for that. I'm comparison, the Audeze has 4 relevant EQ presets for music, so if none of those matched your particular profile, the Mobius would probably sound recessed in the mids. For someone who had perfect midrange hearing (so the Nuraphone adjusted mid-EQ downwards), the Mobius would sound relatively more emphasised or forward.
I guess the best comparison would be between the detail retrieval and overall sonic quality of the reproduction, rather than the overall sound or tuning. Genuinely wish you good luck with your search - hopefully someone will be able to shed a bit more light on the differences between the two.
One other observation - if the bass was distorting in the left earcup, unless three was a driver issue, I'd imagine this could be distortion due to EQ. The Mobius takes EQ about as well as the iSine series from my initial experiments (in other words, very well), so doesn't distort when boosting frequencies - this may be worth experimenting with if you do get your hands on a pair. The warm preset in the Mobius is a completely different tonality to the Default, for instance, with a large amount more bass.