The T90 is something like the T70 but with a bigger soundstage due to its open back. It has also a more 3D like as compared to the Dt990. The T90 is not a better version of the DT990. The Dt990 has lots of harsh trembles and it has a lot more bass than the T90. The T90 has as little bass as the T70, it is a headphone for audiophiles who loves a neutral and clear sound. It has very bright and detail highs, a wonderful midrange and tight bass. The T90 shines at the treble section where its treble let the listener to locate each and every instruments. It has much more instrumental separation than the dt range. As compared with the hd650 or hd700, the T90 will be the clear winner for audiophile who love neutral sounding headphone. I would say it is in a different league as compare to the dt990 as the soundstage is much better than before.