The pads are very similar in appearance to the original Senneheiser pads. It comes with an attachement ring and the foam inserts. The foam looks like it's a tad thicker than an original one. The fitment of the pads IS tricky- there's a considerable force ("considerable" in terms that you're working with headphones, and not pressing the oranges for juice...). For me it felt that it's too much, but I kept trying until the "click". Once I knew how much is needed, the second pad went quicker. My advice would be to try fitting the old pads back on (once you remove them, of course) and do it without a foam inserts. That way you will see/hear how the pads are supposed to click in to the position.
You have to press the pads/ring until it clicks in to place. If you look into the groove around the driver, where the ring is supposed to go, you can notice "lips" on the outer part of the groove at 1, 5, 7 and 11 o'clock position and these are the places where the rings/pads click into the position and that's where you're supposed to press.
The whole process might seem complicated from my description, but it's really not. Watch youtube videos as well.
Finally, the most important part- THE SOUND. Or, better, do the pads AFFECT THE SOUND ;)
As you all know, there is no and there can't be any objectivity when dealing with such claims, therefore it's just my opinion on the matter.
Also, the perceived change in sound is due to the fact that the new pads are, well- new, and so the headphones will (at least innitially) sit slightly different on your head when compared to the old pads.
The sound signature did not change-it's still good old HD650. Nice and smooth and sweet and detailed at the same time ;)
Only perceived difference (in general terms) is more pronounced and punchy low end. Again, this is most likely because the distance between the ears and the drivers is bigger because the new pads are stiffer.
I could not discern any obvious change in highs. Only my mind tried to trick me by saying that if the foam inserts are slightly thicker than the original/old ones, there must be more filtering/damping of the high end. And maybe there is... ;)
O.K. enough of this.
In short- awsome pads. Would buy again.
Fast shipping with a tracking number and nice communication.
Thank you,
Domas