I haven't heard the DFB but I had the DFR before replacing it with the DFC and I agree with your conclusions, everything just sounds better on the DFC (also reviewed using both SE846 and Audeze LCD-4z.Just thought I would share my own personal experiences. I decided to go all in and buy all three dragonfly’s and the chord mojo to do a critical listening comparison of all 4 for my two main daily’s (Shure se846 and 1More Quad drivers). I also play hi res music from Amazon Music unlimited Ultra HD
Dragonfly Black
For the money, this DAC is very impressive. Definitely the best bang for your buck in terms of cost/improvement. Really steps up the music but it’s a very neutral sound signature so nothing really stands out.
Dragonfly Red
A marked improvement on the Black as the bass, treble and Mids are very audibly improved and more forward sounding to my ears. Soundstage is better than on the black but not amazing. It is Bass heavy but still an enjoyable listen.
Dragonfly Cobalt
Not as bass heavy as the Red but everything just sounds better. Much more crisp, detailed and the soundstage is incredible. In my opinion a worthy competitor to the Mojo and worth the steep price against the Red. It just sounds so much more pleasant. Nothing is too harsh but everything just sounds incredible.
Chord Mojo
This is the best of the 4 hands down. Noticed the biggest difference using my Shure se846 but the soundstage was better, instrument separation was incredible, Bass, Mids and Treble all sounded impeccable with nothing muddying over anything else. I couldn’t really hear any difference between the Mojo and the Coablt using my 1More’s or even using my Sennheiser Momentum 3 over ears. Seems the Mojo comes into its own with high end IEM’s like the se846.
Conclusion
The dragonfly’s are all amazing with the Cobalt definitely being the best of the three and considering the transportability and ease of use with it not needing to be charged to use, I would say the Cobalt is the Best Buy of the 3. But if you have the spare money and you do a lot of listening at a desktop or not moving, the Mojo really is just that bit better than the Cobalt. If money is tight, the Black is definitely worth the money. But if you’re going to spend a lot of money on a DAC, I would save that little bit more for the Cobalt over the Red.
I hope this helps anyone considering any of the options. I have since returned the Black and Red and plan to keep the Mojo and Cobalt. Mojo to use at my desktop, the Cobalt for going out and about.
Don't have the Mojo as I prefer the form factor of the DFC for travelling. Use a Hugo2 to power the LCD4zs normally
If (as many say) the mojo comes "relatively" close to the Hugo2 then I would agree to spend the extra on that (consider that the price was reduced by about £100 a while ago) unless, like me, the form factor, charging and apparent interference with cables is an issue. I prefer the portability of the DFC and so stick to that.