OMG, don't start all that stuff! I ran away from the HE-500 thread, and to some degree from the headphone itself, because all this modding and swapping pads stuff was making my head spin. The great thing about the 880 is it's all of a piece; it's just fine as it is, and super comfortable. You can stick any pad you like on there, but it's unlikely to sound better than the one Beyer engineers decided on no doubt after much experimentation.
In any case the Hifiman velours are hard and uncomfortable.