I applied some pieces (8 per cup) of sorb on my HE500 and the improvement is subtle but noticeable. But the most impacting change was on my ATH-ES700. I put 4 little squares per cup and also changed the inner fiber glass pad with melamine foam. They are in another league now. Will try the sorb in my Bose QC20 and will report the result. Thank you for pointing this out.