You do NOT wanna use the velour pads from the 880/990 on the closed back Beyers. You will lose all the bass, and the sound becomes completely treble oriented. You must find ones MADE for the 770, or something made for closed backs.
The 770 velours are completely different from the 880/990 velours.
Oops! Sorry for posting the link then. I just saw EDT 770VB so I replied with the link. :)
EDT 770V on Amazon UK then:
I did try the 770V pads on my COP but I prefered COP's slightly larger bass (I think the only reason I still keep the COP). I've been using the DT 770 (80 Ohms) since I got them and COP is in a drawer. Ahhh~