I personally love the X2, but not for the usual reasons. I think it's the perfect headphone for people concerned about tinnitus.
First off, the frequency response is purposefully scooped in the "harsh" region at 5-7kHz for fatigue-free listening (ahem, HD800). I also find that as I lower the volume, the accentuation of the bass becomes more neutral in relation to the mids and highs. This encourages appropriate listening levels. Finally, the gel driver has none of the ringing artifacts (ahem, DT880) that don't show up as easily during sine sweep measurements but will kill your ears.
Because I care about my long term hearing more than squeezing out that last 2% of audio quality, these have become my main cans. Super comfy and affordable doesn't hurt either.