I have a Bimby and its not a really noticeable difference from the Modi2Uber to me but then I maybe DAC deaf. The way I define noticeable is to let others listen to the various DACs and switch between them with a level matching box. If more than 50% can notice a difference then I would consider it a "noticeable" difference. In the case of the Bifrost MB vs Modi2Uber only 1 in 7 persons could notice a difference so far and most of them were younger with fairly good hearing that could tell the difference between 256 MP3 and WAV files which many can't.
And strangely you have tons of people who swear they hear a (not subtle) difference between the Modi and Bifrost (multibit), some even having done blind tests. What I've also noticed is it depends on your chain. Higher (or maybe just different) grade cans/amps can pick up certain differences that others can't. So it's not just a matter of doing A/B tests, but having a setup that can reveal those differences. You are not just testing the DAC, but testing everything else in your system along with it, since different components react differently to each other. Yes, confirmation bias is a real thing, but also, this hobby seems to be extremely delicate in terms of synergy between components (which is a real thing too), which is why even blind tests may not be reliable. I also find it hard to believe a transparent, down to earth company like Schiit (who are friendly to this forum) would intentionally make a DAC that is several hundred dollars more than the Modi that is not sonically different in some way. I don't really buy that at all. I'm sure they thoroughly test using sophisticated techniques, and if they can't hear a difference, then it means they're no better than the snake oil cable charlatans, since it would mean they're intentionally deceiving people. Anything's possible I suppose, but I don't really buy it.
EDIT: And those younger people with really good hearing, I've noticed that sometimes people need to know what to listen for in terms of differences (depth, transparency, transients, fast/slow, etc) in order to be suitable candidates for blind tests. The difference between a 256kbps mp3 and WAV should be extremely obvious to most anyone with decent hearing, because one is garbage and the other is excellent. Mp3s are not good audio files (it actually strips sonic information from the track). So you have two totally different classes of audio. Whereas with the Modi, you already have an excellent DAC that is not on the level of a crappy mp3 (let's say just in terms of comparison), being compared to a more expensive Bifrost... you are already starting with two excellent sound sources, not one crappy and one excellent (mp3 vs WAV), so it may be harder for casuals (who are not sophisticated with audio terms and sonic levels) to differentiate between the two. In their mind, they both sound great, so this may trigger an unconscious/confirmation bias in themselves, since they are both awesome sounding (just as a matter of deductive reasoning). I have heard stories like this where a wife will not be able to tell the difference between two excellent pieces of equipment that is obvious to the husband, with her reasoning being "they both sound amazing!" These DACs can be enjoyed by anyone, but they were made by sophisticated people who understand and appreciate these subtle, but powerful differences that your average person may not.
But in the end, the individual must use their own ears and decide, confirmation bias or not.
