DACs which I specifically recall using with RNHP:
- Mojo
- 2Qute
- Yggy
- (Current) PSaudio PerfectWave
I may have used more, but do not recall. I saw your thread concerning DACs. Did not reply there because I try to keep my responses brief - concise (in person, you can talk about subtleties. Online it often gets lost in a long post). If you look at my profile, I've gone through about a dozen DACs. What I've settled on as desirable might not suit everyone. But I don't generally think about the DAC. Yes, there's a difference between Yggy and PW, but both play sound through RNHP.
A consistent character of the RNHP - yes, unfortunately it depends on the headphone. I would characterize the RNHP as fast dampening. It matches the fast character of the Utopia (which is not the topic of this thread). When using the HE1K, I would prefer a basic, strong solid state, such as the Jot. Reading your post, Ragnarok is probably better, because it is slightly less lively (not dead - only very slightly less lively). Rag is plenty powerful. There are some unobtanium amplifiers that I liked more. In the still available category, Simaudio Moon NEO 230HAD, using just the amplifier portion, was very good. I could also sit with a MicroZOTL2 and the HE1K all day. That was when I was using Mojo as my primary source.