This and That:
It's small. Good build quality.
I'm not fully sure whether the balls are made of glass or plastic.
All of the labels and logos are finely engraved (an not laser-etched, so they shouldn't fade over time).
The four small grooves are actually there to help stacking the device using thick, round rubber bands.
Decent amount of inputs (micro USB, full-sized optical input, mini coaxial input). Separate USB charging and data sockets.
Poor battery life.
USB oscillators chirp and whine with many chargers while charging.
The quirky balls rotate but don't actually do anything. They're basically just "caps" on top of actual buttons, so one has to press them in in order to actually change the volume etc.
The brightness of the illuminated balls can be reduced adjusted in two steps by pressing both volume buttons. Holding all three buttons during the boot process jumps straight to 3 V output voltage ("Line Out Mode"). Thereafter, that value can be changed.
The Volume Control:
No intuitive volume indicators; volume indicated by the colour of the two volume adjustment balls.
The lowest possible volume setting could and should be lower in order to listen quietly with very/extremely sensitive in-ears.
Rather big step size in the low adjustment range. Gets better (smaller steps) the higher the volume setting is.
I get that it's a very powerful device, but neglecting the possibility to listen very quietly using sensitive in-ears is quite a disappointment.
The last setting is of course saved.
Sound:
The Mojo is an upsampling DAC. According to the designer's statements in several interviews and online communities, it's done to implement several filter design.
No traditional DAC chip but instead an FPGA-based solution running the designer's code is used.
As long as the result is fine, I personally don't really care about what chips or solution is used. Then I also don't care about the company's or designer's bold statements or attitude. Anyway, for many years now, audio devices have clearly exceeded the humanly possible audible threshold, so generally better measured performance is mainly just a bonus to calm one's mind and doesn't add any audible improvement.
The two 3.5 mm headphone outputs output the same signal in parallel.
Frequency Response (no Load):
Here we can see a characteristic as if a slow roll-of filter was used. More on that in a second.
Output Impedance (various Loads):
Various of my in-ears and full-sized headphones were connected directly to my Chord Mojo in the first two graphs. The third one shows the Mojo's output into a separate amplifiers line input.
As one can see, the frequency deviation is not what we would typically see for sources with an (stable) output impedance not-so-close to 0 Ohms. Instead, only the upper/super treble response is altered. That's because in the lows and mids, the Mojo's output impedance is commendably low, however towards the highs, it increases (that's why it's the most linear with high impedance loads such as my Sennheiser HD 800 or most amplifiers' line input (that usually have a high input impedance)).
While it's in the mostly irrelevant or inaudible range for most models, some low impedance multi-BA in-ears already show a deviation that's in the relevant area of the frequency spectrum and with a quantity that is already in the audible range. For a device with such bold claims by the designer, it's definitely a bit of a letdown.
This (that the Mojo's output impedance is higher in the highs than the rest) is by the way also backed up by other peoples' and magazines' analysis and measurements.
Hiss Performance:
Using very sensitive, near-extremely sensitive in-ears such as my Shure SE846 or Ostry KC06A and Pai Audio MR3, there is a mild to moderate amount of hiss audible; in this regard, the Mojo is about comparable to the Cowon Plenue D or Plenue J.
While the amount of audible hiss is still pretty low and while I get that the Mojo is a device with a very powerful output (for the power it's able to put out, the amount of hiss audible with very sensitive in-ears is nearing excellence), I would have expected it to perform a bit better in terms of hiss performance using very sensitive in-ears.
Subjective Listening Impressions:
I'm an objectivist. No flowery descriptions. The vast majority, if not almost all, properly designed audio devices will sound similar in a controlled, volume-matched comparison.
That said, the Mojo doesn't sound fully identical. Using it directly with in-ears (but not those that would make it obvious right away due to their sensitivity and low impedance), it sounds just a touch "smoother"/"softer" in terms of cymbal attack. Clearly just a small nuance and negligibly small in an everyday scenario and even during critical non-comparative listening, but (unfortunately?) reproducible. However, the soundstage also appears to become a little smaller (this is however only something I am hearing with rather low impedance in-ears and none of my full-sized headphones that on the other hand still appear just a touch "softer" in the upper highs). It's not "better" or "worse" but just a wee bit "different" sounding and nothing that I would notice without properly done and exhausting direct comparisons.
Other than that, it sounds just as clean and transparent as any other well-designed audio product.
Conclusion:
Things that aren't as superb and superior as the designer wants people to believe in interviews and online audio communities: volume control, output impedance in the highs, hiss performance aren't flagship quality at all. For a device at this price, and with so many bold claims, one would expect the "best" for the price in all areas; but it doesn't deliver that. While undeniably good, the Chord Electronics Mojo just isn't good enough for what it promises, even though the general measured performance as a DAC is indeed good.
As a stationary device, my RME ADI-2 DAC is superior to my Chord Electronics Mojo in every aspect, and as a portable device, the FiiO Q5 (with the AM1 module) offers the better value compared to the British DAC.