Does the foam feel any different compared to 840 pads? The perforations look pretty large. Based on a series of experiments to ventilate the 840 pads, bass rolls off pretty steeply from 200 Hz with just 6, 6mm cuts in the outside of the pad walls. I wonder what you and others who've tried Alcantara pads on modified T50RPs think about the bass? Did you have to compensate elsewhere to bring the bass up?
Has anyone tried bluecell replacement pads? They're likely from China. They make pads for most popular headphones. The 840 pads from bluecell cost $7 at Amazon.