These sources I use to prove my point that DCA headphones are on the softer side come from not just any person, but from reputable reviewers such as the Headphones.com team and Crinacle who have tried and tested hundreds of headphones in their lifetime. Ideally the best way to prove my point is to use a completely objective source, but here's the problem with that: Nobody posts dynamics measurements online.
If you think DCA headphones have great slam and impact, good for you. But I don't know whether to trust you or the other reputable reviewers who say it has less dynamics relative to other headphones like Focal or Sennheiser... After all that is the only point of reference I have.
Perceived dynamics are a function of distortion, SPL and Frequency Response. Impulse response (aka the whole FR spectrum dissected in time domain) of headphone will show whether it's more or less dynamic than others. Subjectively, Focal Clear dynamics is inferior than the DCA Aeon X Open while Utopia is clearly better than the DCA during my A/B subjective test with them.
Also, I own a headphones.com amplifier BTW and that's feeding my DCA Aeon X Open with plenty of dynamics and slam!