Metrum Onyx versus Metrum Pavane

I stopped reading after you said, "Ive read that Onyx has a narrow soundstage" 

Why, you disagree with this assertion?The impressions I've read are quite contradictory in this regard - hence my specific questions above. Please, feel free to contradict this statement.

To put things in perspective, when I had the Gungnir Multibit in my system for a few weeks I Ioved many of its sound traits but wanted a wider stage, much blacker background, better treble extension (the stuff above ~10kHz, probably), a more relaxed, effortless presentation (difficult to put it into words, it was a bit as if I was kept in a bit of a tension all the time, perhaps something similar to how I felt about my ex AKG K1000 / D class amplifier as opposed to the effortlessness my Stax) and maybe just a little thicker tone (but this latest thing might have been more a matter of synergy). All heard in a couple of solid state systems + my Stax headphones. It was the (supposedly) latest, unofficial "A2" version (November 2017), kept on all the time and with more than 200 hours of burn in.

@don

The issue is, many of your questions are system dependent, as in, what are the speakers and how are they placed in the room.  Anything to do with sound stage is more dependent on speakers and speaker placement than electronics. At this level, the electronics are high fidelity and detailed, there's great channel separation, bandwidth and signal to noise ration. 

Secondly I don't think many have compared the Pavane to the Onyx directly, unless there's DAC meetup, these comparisons are difficult to do.

OS dacs sound different than NOS dacs. Delta Sigma dacs sound different than R2R dacs. Onyx/Pavane are both NOS and R2R. Typically these sound more relaxed than delta sigma dacs, I don't know why. But keep in mind all dacs have a sin(x)/x roll off which is compensated in OS dacs. And you can compensate for that in NOS dacs by oversampling in software before sending to the dac.

Either way, with My speakers and electronics (Legacy Signature SE, Lyric Audio Ti 140 MK2, home built HTPC w/ SSD feeding the Onyx via USB) the sound is effortless, noise free and high resolution. You can check my original review for more technical stuff.  If you name some test tracks you use I can play them and get back to you.

Thanks for your answer and your offer to provide me with further information!
Regarding the soundstage, I have found that various sources (CD players, Dacs) can have a significant impact upon its width. My hearing is probably not trained enough to hear depth or height very well (I’m an avid headphone listener) and my speakers system + room is not very helpful, but I hear the width clearly. I have heard these soundstage width differences easily in speakers as well as in headphohes. So, compared to any other sources you have heard, is Onyx’ soundstage broader or narrower? I don’t have a specific track to test soundstage width, for me it’s pretty apparent on any material. If you need something very specific, maybe, from the top of my head: track 1 "Yulunga: Spirit Dance" from Dead Can Dance - "Into the Labyrinth" (after min. 2:53 or so). For example, the hard panning of the left side maracas at min. 2:53 and the rest of the track following this. This is, by the way, a track I’m using to check for reasonable bass extension (tympani at 2:29 and a few times later - not extremely deep but it’s about my threshold for "reasonably extended") and tactility / snappiness / punchiness (from min. 3:02 on).

As for the highs, I often use the beginning of track 7 "Desolate Mountains II" of Jan Garbareck’s album "Visible World". I pay attention to the actual treble extension as well as to the chromatic contrast between the various percussion "notes" - the Gungnir Multibit tended decrease a bit the highest frequencies, accentuate the mid-treble (8-10 kHz? - I don’t know the exact frequency band) and attenuate a bit the aforementioned chromatic contrast (making everything a bit more uniformly grey and metallic). Small things, but I could hear them clearly and it did bother me. How do you find the Onyx compared to my description of the Gungnir?

I think if I was looking what you're looking for, I might look for a DAC with tubes.  My first choice would be SW1X, which offers an in- home trial period that I think is invaluable.  Given the feedback by owners, this is an outstanding DAC that you're probably unlikely to return.  BTW, if you want another recording with outstanding width, pick up one of these.  A lot of the recording lives 3 to 5 feet outside the speakers.  Don't know if it's a phase trick or not, but it's a really cool recording and great music to boot. 

https://www.discogs.com/Various-15th-Anniversary-Sampler/release/7022235