There is definitely some serious synergy between the 152XS and FlatCap. I’ve been comparing the sound of my 152XS powered from the 200DR against FC2X for quite some time now, and in my last iteration I ran it exclusively from the DR for roughly 3 months, and frankly forgot about it for the most part.
About two days ago, and triggered by this conversation, I swapped the FC2X back into Upgrade 2 for one last try. Earlier A/B tests only revealed subtle differences in presentation to my ears, but after letting the 200DR sink in for longer term the improvement was immediately discernible.
With the FC2X now in place the leading edge of percussion and brass is more impactful, voices get projected forward with better presence, soundstage wider and taller, better defined front to back too.
Needless to say I’m not going back to the 200DR power supply, FC2X is staying in Upgrade 2 for good. I will definitely try a HiCap2 when funds allow.
I don’t deny your experience but if you put the FC2x on upgrade 2 you don’t get the benefit of DR - Naim’s big power supply breakthrough - into your preamp.
In case you are wondering, I have tried my FCXS on upgrade 2 of my NAC152XS with my NAP200DR. Relatively speaking, it was sluggish. So I have it on upgrade 1 only.
Discrete regulators for audio power supplies have been quite common for a long time, they give designers more control over many aspects of power supply performance, no surprise SQ benefits from them. Naim’s adoption of discret regulated technology was more of a needed fix than a breakthrough in my view, regardless of how innovative their implementation may be.
On the other hand, feeding the preamp from the 200DR neglects the sonic benefits of supplying power separately to distinct sections of the 152XS, hardly a breakthrough in itself but more fundamental to the design of the preamp, and possibly more consequential to the end result in terms of SQ.
In the end it comes down to which design feature yields more sonic benefits, something for our ears to decide…Or maybe as the OP suggested, rather be blown away by marriage of both technologies in one HiCap DR.