There are people who write logs about how the Schiit Yggdrasil changes in sound over days, weeks and months. Always getting better of course. Even if there is some degree of change when measured after warming up it's not going to be much.
There are plenty of people talking about the depth of performance with products that don't have any performance.
There are people listening to crappy TDA1547 DAC's and saying they are "the best" when the sound is literally horrible 1980s stereo quality.
If you really want to be seen as the honest broker you portray, and are truly interested in learning. Let the DACs burn in, you stated you also have the higher end Yaggi DAC in house. Listen through a good SPDIF source with your best transducer, you say you have Stax correct? Use the discerning ear and your knowledge of live music that you have also mentioned, and please report your results. You, (like most) are accustom to the sound of delta sigma dacs, they do not sound at all natural, just give it a honest try.
Electrical components don't have burn in that exists in this manner. Any "burn in" is done in the first minutes of the device running.
As capacitors and other components get old they sometimes drift out of spec which can change their performance (and sound) in time. That is about where it ends. The rest of this "warm up" nonsense is just myth created by people who remember the days of Vacuum tubes and needing to hit the correct temperatures to deliver their performance specs. Modern day semiconductors have out-of-box performance that those old components couldn't ever match on their best days, and they are tolerant to voltages, heat, interference, etc.
People like you are the ones who allow companies like Schiit to continue scamming honest people out of their money. I listened to the Mimby in the middle of last year after I fell for their marketing aswell. It sounded like utter trash and contained plenty of artifacts in many of my classical tracks. Also the constant pops/clicks in my quiet tracks really ticked me off. I tried to like it, I tried to believe in the marketing.... but it was just marketing rubbish and in the end I could tell a clear difference between the Mimby and my D30 or M8. Even my wife could when we got into complex violin tracks (she plays violin) and she could tell where there were artifacts or where the tones weren't being played clearly. This was even before I had mrspeakers Aeon or Denon AH-MM400 or Oppo PM-2!
So you feel that difference denotes a bad DAC. I hope I can respectfully disagree. IMO it is like saying if a car needs higher octane gas to stop pre-ignition , the car is defective.
You don't understand how computers work man. The driver is the same as
@amirm has said. Therefore its not Schiit's driver or Windows driver which is defective if other DAC's using the same driver are not experiencing the same problems. This is a flaw in their design which causes these problems, if it was driver related all devices using the same driver would malfunction in the same way.
Don't compare drivers to gasoline and pre-ignition, because the two aren't the same at all. Gasoline octane could be only compared to voltage / amperage for power input as this is the "fuel" that the DAC uses.
Schiit knows this is a problem and this is why they sell their own magic fix boxes which will always perform better because they know of the flaw and they fix it in a second box that they sell you after you have already gotten used to listening to one of their DAC's.
I was actually blocked from posting on head-fi after I found the SMSL X-USB because it does the same thing as their Eitr box but it costs only $55 and uses the newest XMOS. Administrators started threatening me and telling me that I was making "false claims" and that because I "don't have a eitr" I can't "claim it does the same thing". Even though they are literally both products described to do the same thing.
Understand that this is a large scale scam and these guys are all profiting heavily from deceiving everyone. Bad or objective talk about Schiit products results in post curation on most audio forums.
Multiple post deletes/edits results in threats from admins/mods. ( I can actually prove all of this as I have downloads and screenshots of every bit of discourse with the administrators of Head-Fi as I believed they would ban my account or edit the PM's when this type of stuff was brought to light).
I considered starting a forum like this before but the reality is that I really don't have the time to run yet another online community and I don't have the time to do measurements on all this audio equipment on a regular basis (atleast at this point in time). So I'm glad this forum was started because a board like this needs to exist to benchmark audio products as they are advertised vs believe in marketing babble.