Yeah, looks like they send me a DT880 driver without the felt.
I wonder what's the use of that felt. My guess would have been reducing treble or midrange, but it's not like I've got loads of midrange and killer treble without it... Less midrange than with my MS1000 and more treble. That's not a big surprise, though. Treble doesn't seems as ear piercing like the 250 Ohm systems' at higher volume.
Judging by sound is really hard after two weeks of MS1000.