Ok, here's what I thought whilst listening...
Paco de lucia, Al di Meola, John McLaughlin - Mediterranean Sun Dance / Rio Anco, album Friday Night in San Francisco
Yggy, better tone, digs deeper than the Audiomat.
NuPrime more clinical in its delivery than the Vivere, Vivere better at instrument separation.
Jethro Tull - Locomotive Breath [40th Anniversary] and Pink Floyd - Mother, album The Wall (Discovery Edition)
Yggy, more pronounced kick drum, good instrument separation, Audiomat kick drum a little less obvious in mix, Vivere on par with Yggy re kick drum. Both Audiomat and NuPrime had less visceral impact from kick drum.
Pink Floyd - Goodbye Blue Sky, album The Wall (Discovery Edition)
Here there little between any of them, the Yggy and Audiomat do better resolving some of the finer detail, but guitar sounds great on all
Emmylou Harris - Goodbye, album Wrecking Ball
Yggy and Audiomat deliver more warmth and detail, especially vocals and bass.
Emmylou Harris - Boulder to Birmingham, Producer's Cut
Yggy more musical warmth than Audiomat, better at conveying emotion of the voice.
Vivere has more warmth than NuPrime, without sacrificing detail.
Patty Griffin - You'll Remember, album Children Running Through
Patty has a wonderful, incredibly powerful voice, that does a great job conveying emotion, but it's also a lethal weapon and can make your ears bleed when she hits the high notes. The outcome here surprised me. I found her voice as she hit the highs most shrill on the Audiomat. The most refined delivery came from the Yggy, then the Vivere, followed by the NuPrime.
Keith Jarrett, Koln Concert, Pt. 1
Again the Yggy has the upper hand and the Audiomat comes off as more strident. Vivere comes off as more refined/ less strident than the NuPrime. Audiomat and NuPrime more or less on par here.
Dire Straits - Private Investigations
Vivere more musical than NuPrime. NuPrime comes off as more clinical, doesn't have the warmth of the Vivere. Not a lot in it between the Audiomat and the Yggy, the Yggy is warmer without losing detail.
So, to summarise...having spent most of last night and the better part of today listening...
Order of preference: Yggdrasil, Audiomat, Vivere, NuPrime.
The Audiomat just nudges in ahead of the Vivere, but the Yggy is a clear favourite and the NuPrime clearly last for my tastes.
All of these DACs are very detailed, all of them are musical and none are fatiguing. The differences are subtle and lie on the warm/organic > analytical/ clinical continuum as well as the DAC's ability to convey the finer subtle details and body of the recording.
The most consistently engaging DAC for me was the Yggy. It does a great job at conveying detail without ever presenting as analytical or clinical and stuck me as the most balanced / even handed regardless of the type of music or instrument being played. I've listened to gavinbirss' Soekris plankie on my system and it's very close to the Yggy. The Audiomat surprised me, if it were less strident (and it's not obviously strident) it'd be on par with the Yggy in many respects. Make no mistake, the NuPrime is no shabby DAC either. It's detailed and musical, but doesn't convey the finer subtle details as well as the others and it has a tendency to present as clinical at times. In many ways it reminds me of the how the Vivere sounded in the initial stages of its voicing as Gert iteratively worked through feedback from myself and others over a period of many months. My final realisation is that the Vivere is, to me, a lot better than I had appreciated. There were many moments during this shootout where it wowed me and brought a big smile to my face. In addition to being an electronic wunderkind, Mr. Byleveldt is an artist, whether he likes it or not.