After receiving my HD6XX last December I compared them to my HD650's. I discovered that the 650's were in need of new ear pads. I swapped my brand new HD6XX pads onto the 650's and it freshened up the sound. Instead of getting the stock Sennheiser pads for my 650's I decided to give the Dekoni Elite Velours a try. I can confirm that these pads increased the bass as well as making the soundstage slightly more forward. The change was not majorly so but enough to audibly distinguish them from my HD6XX. I joined the HD58X drop back in mid February and there was a lot discussion on the Massdrop site about the lack of bass that the early reviewers commented on. I commented myself that anyone concerned about a lack of bass could consider the Dekoni pads as a way to increase the bass. Of course, as we all know, the 58X was re-tuned in order to increase the bass. From what I have been reading it sounds like there is more than enough bass due to this re-tuning. I haven't received my 58X yet (hopefully next week) so I'll assess whether or not Dekoni pads are even necessary. I suspect that they won't be required though.