To be fair this was the previous stuff not the Apex module described in the statement about tools.They mastered the marketing, it's so simple.
Brutal reality shows that there is 6dB difference in SINAD. It's a lot.
https://goldensound.audio/2021/10/12/dcs-bartok-with-headphone-amp-measurements/
I imagine though that their statement was in reference to the mapper/noise shaping because yeah, basically no analog devices can measure as low in level as many modern noise shapers are able to work to.
Chord's one is accurate to -300dB for example.
Their statement references linearity in general which is a different story but the statement could be taken in many ways