I didn't feel the ups and down were that bad or something that stuck out that much. Although compared to something more flat and neutral like the HP1000 or UERM, you could certainly hear the unevenness in FR. They aren't sharp peaks - so that's good.
Here is a graph comparing pads. Pads (Green + Red). No Pads (Blue + Orange). Looks like the pads push down the bass a bit and bring out 10kHz