Unless it is specifically mentioned, I’ve taken the view that it is not used in an item, most likely due to cost or physical space. While the Nap200 didn’t mention DR, it was only used in the power supply to a preamp, if that part got used.
If you look at the internals of say an NDX2 you can see that the PSU section is quite basic - various transformer taps go through rectification and smoothing. No fancy DR regulator boards.
Many devices do include additional further regulation across various boards, or for powered DIN etc,
This is the naim way - you add an external PSU to increase the quality of the power rails and hence SQ.
The XPSDR has fewer DR regulators than the 555PSDR which was one reason for the cost difference (let’s not start discussing VFM again).
DR regulators can be found in the NAP250DR, NAP300DR, NAP500DR, XPSDR, PS555DR, 200DR (DR power for attached preamp, not the power amp itself), Supernaits 2 and 3 (DR for preamp only), Hicap DR, Supercap DR.
I was only looking around the forum to try and find a post from 110db about the regulation in the bare NAC332, as I wasn’t sure if that was DR vs some other regulator scheme, can’t find the post I thought I recalled so far!
With all due respect to Dr , it’s no longer new and probably just seen as a std part now in new Naim , no need to advertise ,it is after all over 10 year old development