As promised, some thoughts on the Hex and the Yggdrasil. I had an Yggy here for a few weeks, of which the Hex overlapped by a few days so I was able to compare them directly. I was able to A/B them via multiple zones in JRiver on the same Asus G751 laptop (Windows 10), with both DACs feeding into a Schiit Ragnarok and on to my HE1000 headphones via 4-pin XLR. Both DACs were connected to the amp via their XLR outputs.
Here's a snippet of some earlier thoughts I had about the Yggdrasil when comparing it to a couple of good Sabre dacs I have. These thoughts also apply to the Hex: I hear the biggest difference in voices...the minute textures in, for example, Nick Drake's voice on "Way to Blue" are totally smoothed over on the Sabre dacs, whilst the Yggy is showing me all these little micro-sounds that make his voice so much more human. When he holds a note, I'm hearing the slight rasp in his voice....think in terms of a slightly jaggedy horizontal line, whereas the other two dacs show a straight flat line, more of a one-note sound. I've heard this song probably hundreds of times...never heard these little details. The Yggy also avoids that uncomfortable mid-range push you can sometimes get when a voice gets stronger/louder momentarily...on the Yggy these ebb and flows of volume sound natural, whereas the other two dacs both exhibt that annoying (to my ears) push.
When comparing the Hex and the Yggdrasil, it's more of a level playing field as to my ears they both exhibit a similar level of micro-detail retrieval and avoid the weak points of the two Sabre dacs I have. I did hear some differences between them though. The Yggdrasil puts the details a bit more in your face...it's "overtly" detailed, if that makes sense, whilst the Hex has a less showy presentation, a bit smoother and perhaps more realistic/natural. For short periods of listening, I think the Yggy could be considered a bit more fun, whilst the Hex kind of grows on you over time. I often listen for many hours per day, so the easy-to-listen flavour of the Hex is fine for me. This doesn't mean the Hex isn't engaging...it certainly is...it's just a little less "hifi" sounding than the Yggy. I did detect a slight dryness overall and a lean-ness in the bass of the Yggdrasil compared to the Hex, but we're only talking small differences here. One thing I will say, I tried the Yggy in my speaker system and it presented a 3D image of the music that I really enjoyed. If I were shopping for a DAC for that system, then the Yggy would probably be my choice at this price point.
For my headphone system, honestly I'd be super happy to own either of these DACs and if I was faced with paying the same price for either it'd be a really tough choice. One thing I do prefer about the Hex is the form factor. The Yggdrasil really is a big ugly beast, although of course this may be irrelevant for many people. The extended warm-up characteristics of the Yggy are also a bit of a bind in some situations. As it stands, I had a chance to buy a new old stock Hex for well under half the price of a new Yggy. For that price differential it' was a no-brainer for me, so I now own a Hex. I'd still quite like an Yggdrasil for my speaker system though!