@PWGuy you're in luck! I've now owned the X12, Bimby and Mimby (Bifrost Multibit and Modi Multibit), and here's snippets of my impressions from another thread:
Initial impressions with Bimby:
Several A/B comparisons with my former Gustard X12 DAC reveal the Bimby has more micro-detail and organic / layered bass, and without being colored, has a larger / more expansive soundstage! Yaaay!! Looks like all my focus on multibit / R2R DACs vs. Delta Sigma have been well placed!
Later impressions:
After just finishing a multiple A/B critical listening comparison of my delta-sigma (DS) vs. multibit (R2R) DAC, the differences I've notices were huge and far encompassing. Generally you get a much more organic / lifelike sound with larger soundstage & imaging that's much more 'out of your head', and better defined layers - making the delta sigma DAC sound 'brittle' and artificial after listening to the DS.
(somewhat later)
A seasoned industry insider / hobbyist told me the Bimby DAC is slightly darker tonality, as well as the Elise and HD 650 (he's tried my Elise also). I'm sure he's mistaken on the Elise amp, but I'll tell ya my ears yearning for more detail / linearity. I like the Bimby enough to keep it though for it's realism, but it seems as if this pairing is dark enough to oust the HD 650 for now, which is also darker than neutral, even with my mod.
My Bimby not only seems dark-ish, but also a smidget too euphonic / colored which further hampers its' pairing with the Elise (making it double colored), necessitating 'colder' / brighter sounding tubes, which may prove a struggle. I bought this DAC new and still have a few days in the 14 day return period.
Initial impressions with Mimby:
Compared to my Gustard X12, it’s a big step up! Markedly improved transient response (slam of the dynamics), more ‘focued’ imaging, more detailed, and a superb realism. Everything sounds absolutely engulfing / enveloping, tonally perfect, crisp, yet clear and clean as a whistle. Yet seems slightly musical and/or euphonic. Compared to the Bimby at twice the price, this has better dynamics / clarity and slightly less euphonic (a good thing), while the Bimby has slightly better imaging and soundstage.
Sounds like a $1,000+ DAC, all crammed into a tiny little box for several hundred! Absolutely the most staggering price to performance of a DAC made to date. Only downside yet is soundstage seems slightly small. And this is only without burn-in and using mid-tier tubes!"
Update several days later:
My initial impressions remain unchanged, and I really think the Mimby is a game changer, and an unwavering performer! It does seem to have slightly less soundstage and ability to handle multi-layered bass than the Bimby, but that is more than made up for by its' vastly improved transient response, more neutral / less colored and cleaner sound sig. Yet my tastes still yearn for a slightly dryer / colder sound, so I may still compare other multibits such as the Gumby at some point. But for now I'm absolutely satisfied with this little DAC. Also being a former owner of the Modi 1, this is an astronomical step forward! (mainly in resolution and realism)