I just got the Tascam TH-02 headphone and unboxed and started demoing it.
Sadly, my impressions are quite negative. It has a lot more actual perceived resonance than I had led myself to believe, even more than a ATH-m50, perhaps a less pleasing resonance or something. When it comes down to it, it is also too dark in the upper mids and lower to middle treble for my listening habits. On the bright side, the bass to middle midrange is quite linear and driver response is quite fast. Is it a game changer and giant killer for me? Well, honestly, no--bass is nice, but detail is pushed back in favor of it though the detail is certainly there.
For a quick comparison, I already would rate the Tascam TH-02 well below any run-of-the-mill Grado and Sennheiser headphone and many times below my Superlux HD681. I will probably be posting these very soon for sale. It is just not good enough for my purposes and it will collect too much dust between my SRH-940 and my Superlux HD681.