How do you use your RNHP? which input? A B or C? and what cable? I found it pretty surprising you said that the rnhp had less resolution than the Mojo 2 alone lol, I suspect you could be using a not that good cable and using it with RCA , which could be introducing some noise and as a result less dark background=less clarity and detail.
I have 2 burson soloist 3XP with Supercharger and a power filter, and I use the gryphon via a Japan Canare 4,4MM to XLR to the balanced inputs of the RNHP and I consider it to have excellent resolution, it has pretty great clarity and resolution.
The negatives of the RNHP for me could be: It lacks some soundstage size compared to the soloist but it is better than the gryphon, it could sound sterile in comparison sometimes, also treble refinement is not that good compared to burson.
This is all with the stock PSU, mine has very dark background, no hiss, some people had issue with this, not issues with mine.
I tried to buy the meanwell PSU upgrade to try it with the ifi iPurifier DC2 which I already have, but the package got lost, with the PSU upgrade+the purifier it could be even better, I'm pretty sure it will have even greater clarity since the burson gets more clarity with the ipurifier DC2
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In short words I don't find the rnhp lacking in resolution or clarity, when using the Balanced output of my dac into the XLR input of the RNHP, it has excellent clarity and resolution and my complaints or things where it is not that great would be in other things.