I may give this a try when I get myself some double sided tape. I honestly can't see this making a tremendous difference as the velour ear pads seem snug enough with the cups to begin with, but it doesn't hurt to give it a whirl. I'm no expert, so it very well could have an impact!
Would Jerg or someone else recommend doing it for all 4 sides of the mounting right if you aren't using the back vent?
That is what I have done, can't do any harm can it?