What headphones did you have previously? If you had something like the XB1000 as your previous headphone with hugely elevated bass, you might think you're not hearing it when you actually are because you're not used to the bass of the MDs. Try getting a sine wave generator and playing notes at 30-100hz and see if you can hear them at all.
I've had tons of different headphones (mostly in-ears) and previously had some cheap gaming headphones. Even my old IEMs had more bass. And the minute I received them, they had the Alpha Pads pre-applied, so I didn't tamper with anything. I'm not expecting the headphone to shake from bass, but I literally just don't feel ANY impact. I put on some pretty bass heavy music and didn't find it.