Remember that pads are also part of the "enclosure" of the drivers, they are analogous to room treatments (except in miniature).
So, Alpha Pads will change the sound of any headphones where they are used to substitute for existing different pads.
In other words, your Denons, HiFiMans, etc. will sound different in unpredictable ways.
In fact, this was responsible for Dan's change in tuning from 3.0 to 3.2 - it was to compensate for the different sound due to the Alpha Pads.