There's already been plenty said about the R01 unit on here, so I'm late to the party, but I've had mine for some weeks now and thought I'd chime in with my impressions.
First of all, thanks to everyone in this thread who gave their thoughts earlier. It seems like so often on head-fi I read other people's impressions, or check out reviews online, and then when I finally hear a product for myself I hear something completely out of line with what I expected based on reviews, or wonder "why did no one mention X"? etc. But with the R01 I felt everyone did a great job of summing up the slightly-difficult-to-describe sound signature, and how it sounded to my ears matched exactly what everyone else had been conveying.
I've been comparing it directly to Mojo, Plenue S and R2, and owned plenty of DAPs in the past to compare from memory (although that can be unreliable). The R01 is in many ways well ahead. As everyone has said it sounds "natural", and although that is a very vague term that seems to mean different things to different people, what I mean is that the mix just sounds right and "expected" on the R01 with nothing out of place. There's good bass, treble, sense of space and imaging, lack of treble glare and fatigue and all that, as has been mentioned plenty of times now already. Unfortunately I only have single-ended cans so haven't been able to hear the balanced out yet.
One thing that stands out is the instrument separation and layering - or as I prefer to think of it, the ability of the listener to be able to hear an instrument and follow it along through a mix. I find it easier to follow specific instruments with the R01 than with any unit I've owned before.
I also hear what others have said about how the sound signature of different albums sounds more distinct on the R01. As I think Andykong said earlier, different albums should sound different - but it's more noticeable with R01, and it's been quite interesting to hear how different mixes have more of their own character with the R01.
As for the N6ii itself: it's easy to use and the battery lasts ages. Which is pretty much all I care about in a DAP
All that said, I have found that quite often over the last few weeks I find myself reaching for my other DAPs, and it's taken me a while to figure out why I've been feeling like that. I think it's because I get from them more of a sense of urgency to the music, for lack of a better word. It's not like the R01 is relaxed - I don't think that would be the right word to describe it. I find myself wanting to say that instead of the player cranking out sound, it's like the electronics in the N6ii/R01 is feeding the digital signal into all those resistors, and then it just flows through them and out of the player like water - unhurried and even, whereas the Plenues and Mojo I have at hand deliver a quicker feel to proceedings. I know that may sound strange as obviously they are all playing at the same speed and tempo; but the sense of speed or urgency in the music is different, where the R01 has not necessarily a relaxed feel to it, but a more unhurried way of going about music reproduction.
Going through these comparisons it seems I've discovered that I do quite like the greater sense of speed and urgency that I get from the likes of the Plenues or Mojo - I listen to plenty of metal so that may be a factor in enjoying the more urgent delivery of music I get out of those players - the downside being they don't deliver the same sense of separation, imaging and balance etc. The R01 is the only R2R DAC I've heard so I don't know if that feeling of an unhurried sound is typical of all R2Rs or just a feature of the R01, but I get the feeling from other descriptions it may be characteristic of R2Rs in general.
I had been holding off posting thoughts until I had a better idea myself of how I feel about it, but even after a few weeks I'm a bit confused by the sound signature
So amazing, and I love it, but I also find myself reaching for the PS or something instead. It definitely has it's own thing going on and is noticeably different - and in many ways I mean different as in better - than any other portable players I've heard in this hobby. But I still haven't figured out if it's for me ¯\_(ツ)_/¯.
To be honest I haven't even tried the A01 card that came with my unit yet.
