September 13, 2018 16 min read 18 Comments
Review written by Ian Dunmore (@Torq)
AudioQuest introduced the original “Dragonfly” USB-stick DAC/amp in 2012 and it rapidly received a good deal of, well deserved, critical acclaim, both for it’s convenience but also for delivering arguably the best performance in its class at the time. The “Dragonfly Black” and it’s sister, the “Dragonfly Red”, are the latest USB-stick DAC/amps (sometimes called a “dongle DAC”) from AudioQuest. It supports PCM bit-rates from 44.1 to 96 kHz at 24-bit depth and can support MQA rendering with suitable player software. It does not support native playback of DSD material. It is driverless on all major operating systems, including Windows. Power output is 45mw per channel into 32 ohms, with an output impedance of 0.65 ohms and a 1.2 volt drive limit.
One of the nice things with USB-powered DAC/amps is that as long as the device you’re connecting it to, e.g. your laptop or phone, has power - then you have music. Of course, the trade-off is slightly reduced battery life on your device. But in most travel scenarios I find that trade-off more than worth it, as it is one less device to have to remember to charge.
The unit is based on the ESS 9010K2M DAC chip which, despite being the entry level 90XX series “Sabre” converter, still boasts some decent specifications. Of note are a claimed dynamic range of 116 dB and a THD+N of -106 dB. The output of the DAC chip is fed into a dedicated headphone amplifier that features a 64-step digitally controlled analog volume control.
The USB interface is implemented using Gordon Rankin’s “Streamlength” technology. This yields an asynchronous USB interface that keeps the sample word-clock where it belongs … under control of the DAC. While not a new thing today, where every USB 2.0 Asynchronous DAC does this by definition, the “Streamlength” implementation achieves it without having to comply with UAC2 - which makes it driverless even with earlier (pre -Windows 10 - “Creators Edition”) versions of Windows.
To focus on the performance of the Dragonfly Black as a DAC, without regard to output power etc., I also fed it through my SPL Phonitor x amplifier (single-ended, using an AudioQuest “Golden Gate” 3.5mm (1/8”) TRS to RCA cable).
The majority of the music I use in my evaluations is in “Red Book” CD format (16 bit, 44.1 kHz), most of which comes from CD rips; an initial playlist for my audition listening can be found here. Where appropriate/referenced I utilize a number of high-quality, high-resolution, albums, needle-drops, and also some native DSD content.
It’s a solid little USB thumb-drive-sized device, with a soft-touch matte-black coating. The USB connector type-A connector is gold-plated, as are it’s contacts, and is mated to the units case in a manner that exhibits no flex or movement at all. It won’t be the Dragonfly that fails if you wiggle it around when connected directly to a computer. Similarly, the 3.5mm (1/4”) TRS headphone socket is firmly embedded in the device, with no room for movement, and engages securely and positively.
There is not much to speak of in terms of a package. There’s a friction fit cap for the USB connector, finished in the same soft-touch coating as the main unit. And there’s a sturdy little leather pouch to protect the thing from scratches. That’s pretty much it, and that’s really all that’s required.
The Dragonfly series are designed to be plugged straight into a typical USB-A port, as found on myriad desktop and laptop units. As mentioned above, the connector on the unit itself is more than sturdy enough for this purpose - but depending on how the ports on your machine sit, you may want to use a short cable between the machine and the Dragonfly. To use it with newer laptops featuring USB-C connectors, you’ll need an adapter - and again I’d recommend one of the short cable-style adapters vs. the inline “hard” ones.
Using the Black with an iOS device requires either Apple’s Lighting to USB Camera Adapter or Lightning to USB 3 Camera Adapter. Older, pre-lightning, devices may work with the original “Camera Connection Kit”.
For Android-based devices, you’ll need a USB OTG (On-The-Go) cable. It’s worth doing some research on compatibility with your specific device here, as there can be some hiccups with volume control. AudioQuest have made a couple of updates so far to address this, but I cannot say with any degree of certainty how comprehensive they are
The Black and Red dragonflies are firmware updatable. The process is very simple, both for Windows and Mac; download the updater, run it, plug your Dragonfly in, and hit “Update”. Several updates have been released since the unit’s initial update. Most of these have addressed things like volume control issues with Android devices.
Of note is version 1.06 (and later). This added support for MQA (Master Quality Authenticated) rendering, when combined with a player/source that could do the initial “core” decoding.
The current firmware is version 1.07, and this was the version that was used in my listening/testing.
When paired with “appropriate” headphones, the Dragonfly Black is a quite satisfying listen, and certainly an easily-discernible improvement over the typical built-in outputs on most laptops and smartphones. And not just in terms of available power, which is about 3x that of typical built-in headphone outputs - but in reference to overall quality.
Overall tonality is neutral, with no notable emphasis nor reticence across the entire spectrum. Music is presented in an even-handed and balanced fashion. The lowest notes on a double-bass have suitable density and mass while the shriek of a tightly fingered violin, being played aggressively remains suitably biting and shrill.
Timbral rendering is quite natural. The initial attack or bite of plucked strings or percussion might be slightly less immediate than more complex converters/amps, but decay and natural reverberation are rendered well. Feeding the Dragonfly into an amp helps here, and while not necessary, especially for portable use, neatly restores what little bite is sometimes lacking - which suggests it is the Black’s amp that is subtly holding things back.
The bass performance of the DAC portion of the Dragonfly Black is quite solid - though it requires the right match in terms of headphones/IEMs in order for the internal amplifier to be able to keep up. Feeding the output into an external power amplifier shows that any shortfall in bass capability here really does result from running out of drive capability. As such, a bad pairing with your cans will result in bloomy/uncontrolled bass delivery and will also muck up everything else as the unit runs out of grunt.
But into an appropriate load, bass rendering is fully extended, well textured and properly tuneful; spin Dead Prez’ “Hip Hop” (Let’s Get Free) for a lucid demonstration of the Black’s ability to render a musical baseline … and not just a low-toned throbbing.
In a word? Lovely. Smooth, even, lucid and pure. With bass-light mid-80’s synth-pop (e.g. Depeche Mode, Erasure), the mid-range steals the show. Even when driving harder loads the mids remain composed and present. Complex vocal harmonies are easily separated, instruments whose fundamentals live in this space have good body and tone. Big classical pieces maintain good coherence, as do complex mid-centric mixes. Integration between midrange and both bass and treble is smooth and without issues. Detail in the mids seems a bit more vivid than with the treble, though this might be due to other factors with the treble rendering obscuring them.
The upper registers exhibit a hint of grain and modest unevenness. This manifests itself as a little too much bite with brass instruments, and a somewhat steely edge to cymbals, and contributes to the occasionally “tense” or “strained” feeling to the unit’s top-end. Treble balance is proportionate; there is no undue emphasis here - though it can sometimes sound that way if pushed hard into a demanding load.
Instruments with high frequency fundamentals and/or overtones can sound a tad strained at times - though this is typically only audible in sparser pieces or, again, when pushing the drive-capability of the unit. Pairing with smoother sounding transducers, or those with a modest high-frequency dip can help ameliorate these, rather minor, traits; as can ensuring you’re using transducers with more modest power requirements.
How well these factors are realized are heavily influenced by the headphones you choose to pair with the Dragonfly Black. Removing power-concerns, by listening through the SPL Phonitor x, it is clear that the little AudioQuest is resolving enough for any headphone it is likely to be paired with.
Transient response and dynamics, particularly micro-dynamics, are clearly limited more by the built-in amplification than by the capabilities of the DAC. Into easier loads, transients are fast and crisp and dynamic transitions carry appropriate weight and slam. When pushed into too-demanding a load, the response becomes somewhat muted and the raw, sharp, leading edges of percussion, brass and plucked strings can get softened/rounded off.
The Dragonfly models are really intended to be used to directly drive headphones. This means that their performance is the result of a combination not just of the internal DAC and amplifier combination - but is also heavily affected by the drive-requirements of your headphones. Used in a “dual mode”, as a DAC/amp on the go and perhaps as a pure DAC feeding an external amp for a desktop setup, you get “the best of both worlds”. Specifically, a competent and enjoyable fully-portable DAC/amp for use on the go, and then the ability to side-step the power-limits of the amp when used at home. And it is from the amp side of things that, with more demanding headphones, any issues - minor though they are, especially given the market segment hit unit is aimed at, seems to arise.
One odd, but notable, aspect to the audible performance of this unit is that is seems more “settled” and “natural” when rendering content that is natively using a 48 kHz-based clock (e.g. 48/96 kHz material). Without pulling the unit apart, I can only speculate as to why; I suspect the unit is using a clock that is an integer multiple of 48 kHz and requires a non-integer divisor/multiplier to synthesize the 44.1 kHz timebase.
I am not a big fan of sample-rate conversion - but in the case of the Dragonfly Black I would, where possible, use high-quality software-based resampling, such as SoX or iZotope (i.e. ideally NOT that built into your OS) to bring typical CD-rips (44.1 kHz) up to 48 kHz.
Most DAC/amps have enough power that matching/synergy with various headphones tends to come down more to tonal preferences, and other technicalities. With USB-powered DAC/amps, the available power is typically much lower and in many cases careful attention to what you’re pairing it with is required. To that end, I decided to test with some common, well known, and popular headphones, including some that I thought might provide a bit of a challenge for the Dragonfly Black, and comment on them a bit more specifically, than I would typically do for a more value-oriented component.
One thing to note here, is that with IEMS, when using Windows & TIDAL as the source for the Dragonfly Black I had very little room for volume control. The first step above minimum was already a reasonable listening level. By the third step it was bordering on being too loud. On macOS there was a wider range of usable volume adjustment available, but by the 25% mark things were too loud once again. From iOS almost the whole volume range was usable, while still being able to get to a point where it was louder than I would ever listen.
This is an excellent pairing. The Dragonfly Black has more than enough power to make the ER4-XR sing (not that they require much), and their signatures are entirely complimentary. The gentle top-end roll-off of the ER4-XR seems to temper the slight graininess and unevenness of the Black’s treble (the ER4-XR’s treble is so smooth in general that it’s definitely the Dragonfly yielding that grain). The subtle bass emphasis of these IEMs helps bring the overall tone to a very natural place. Bass may not be the absolute cleanest you’ll hear, and there’s some minor bleed into the midrange, but the overall presentation is detailed, nuanced, natural, entirely coherent and extremely enjoyable.
A common problem with sensitive IEMs is that they’re prone to hiss. The 45 ohm impedance of the Etymotics helps mitigate this even with noisier sources, but at normal volume levels, even with no music playing, there’s no audible hiss here at all.
This is another excellent combination. The low output impedance of the Dragonfly Black helps keep tonal issues with the multi-BA-driver Zeus XR in check, and there’s ample power on hand to drive these to ear-bleeding levels. The extremely detailed, smooth and nuanced treble capabilities of the Zeus XR aren’t exploited as well as they could be by the Black, since these IEMs do provide an absolutely transparent window into the minor treble grain audible from the AudioQuest unit - but at the same time they do not exacerbate it. Bass delivery is powerful and controlled and retains excellent texture. And, the mid-range remains the highlight of the show … which is to be expected as it is the strongest aspect of both the Dragonfly and the Zeus.
If you’re very sensitive to hiss with IEMs you will hear a little here when no music is playing or in longer silent passages. However, it is absolutely inaudible the moment the music starts, even when that music is at a very low level.
This starts out as deceptively decent pairing, particularly with regards to overall tone … at least within certain limits, i.e. at low to moderate volume levels - but this deception doesn’t last beyond that and the Dragonfly Black rapidly runs out of steam here. While you can get decent absolute volume levels (over 100 dB), once you start pushing past about 85 dB, drive/authority becomes audibly lacking, bass articulation and control starts to fall apart and the rest of the rendering becomes distinctly “shouty” and “uncouth” in character – especially with vocals.
Musical peaks, similarly, are a problem even with a baseline level of 80 dB. And even at lower listening levels, bass seems slightly emphasized and a bit flabby vs. my normal references; something I’d attribute to it being less well controlled - due to lack of power, rather than an increase in actual level. And these control issues, and issues with level/dynamics, are enough to make me think you need to look elsewhere to drive the HD650/HD6XX combination.
The HD660S are marginally easier to drive, with only a slight increase in sensitivity - but having half the impedance of the HD6XX/HD650 means the Dragonfly Black can push further before running out of voltage; this is immediately apparent when they’re compared back-to-back. You can run things usefully louder than you’re likely to want to listen before their presentation starts to come unglued. When that inevitably happens, it’s a more graceful, progressive and less stark change than it is with the HD6XX/HD650.
Bass is much better controlled here, with greater slam and textural rendering, and does not exhibit the same sense of emphasis as with the HD650/HD6XX (even accounting for the HD660S slightly leaner native bottom-end). The midrange is present, even, and there is no sense of “veil” here at all (a common complaint with earlier copies of the HD650). The slight grain of the Dragonfly’s upper registers tends to exacerbate the less-than-perfectly-smooth treble region on the HD660S themselves, however - and those particularly sensitive to treble issues may find that “grain” becomes “grit” with this pairing.
I sat listening to this combination for a lot longer than I planned to. I’m not even a particularly big fan of the HD660S (I prefer the HD650 in most cases), but this was a solid performance and was easy to get lost in.
These seem to be a lot less power-hungry than I remember them being. They were very well behaved with the Dragonfly Black, playing loud while remaining coherent. Bass remains well controlled until overall levels are too hot to handle. Stage is, interestingly, rendered a little wider than I’m used to with the AKGs, though not to a degree that resulted in a lack of body or a sense of things being diffuse. Treble was a little prickly compared to the best pairings here, which is likely a combination of the headphones and the minor grain from the Dragonfly itself. If the K7XX is your preferred way to listen in general, then this is an entirely competent pairing. And for a total of under $300, it’s pretty hard to beat value-wise.
It’s between this, or the Clear (and/or Elex) for the best full-size headphone pairing I tried with the baby Dragonfly. It just works. The synergy is very good with this combination. Dynamic performance takes a big step up, the scale of music seems to increase, and the general feeling of body to the delivery becomes more substantial. Yet the results are articulate and fast, with detail levels remaining high and excellent transient performance. At no point does this become thick or muddy and instead retains a pristine nature from bottom to top.
When things get very energetic at the bottom end then at very high volumes there’s a very modest sense of additional bloom to the already sturdy bass delivery of the TR-X00. Otherwise the bass performance here is the best showing of the Dragonfly Black with any of the full-size cans I tried it with - being articulate, fully textured, taut, tuneful and generally very well behaved. And it hits hard enough to be very satisfying with solid sub-bass presence.
The pairing of the Dragonfly Black with the Clear or the Elex might just be my favorite way to listen to it. It’s a close-run thing with the Fostex TR-X00 - and which way I would go would likely be dictated more by what I was going to listen to than anything else. The Clear and Elex, tonally, have a very similar profile, and nothing about the Black upsets this. Both headphones are more than efficient enough to play usefully loud, the Clear a bit more so. At very high volumes, well beyond what I dare listen to for more than a few moments, a little stridency and uneasiness becomes apparent, and this occurs a little earlier on the “dial” with the Elex but we really are talking about excessive volume levels at this point anyway; not an issue unless you listen very loud.
The Elex are a little more forgiving than the Clear, as the improved resolution of the Clear is sufficient to more readily expose the slight treble grain of the little Dragonfly, where this is somewhat rounded off with the Elex. And the Clear deliver a slightly more articulate and impactful bottom end, but bass levels are similar enough that I can’t tell them apart. The excellent dynamic properties of both cans are largely preserved, if not quite matching what they’re capable of with a more powerful or refined amplifier.
If I didn’t already have the Dragonfly Red, I could easily see tucking the Black into the case that comes with the Clears and using that combination as my “destination” headphone setup (what I use when traveling and I get where I’m going, rather than while actually in transit). It’s inexpensive enough to buy just for that purpose and leave it in the headphone case.
While a proper discussion of MQA is well beyond the scope of this review, it's worth noting that nothing special is required to play back MQA-encoded content. It'll work on any PCM-capable DAC (which covers pretty much all DACs) and from any player/source. If, however, you want to take advantage of the "features" of MQA, then you either need hardware, software, or a combination of the two that can handle the "decode" and "render" steps to get the full effect.
"Full MQA Decoder" hardware, like the Meridian Explorer 2, can do both the initial decode and the final rendering steps itself - no special software required. Some software players, including Roon (both desktop and mobile), Audirvana+ and the native TIDAL desktop clients, can do the first-level of decoding - which will also work with pretty much any DAC (no special hardware required). And then there are DACs that can only do the "rendering" part and must be combined with software that can perform the initial MQA-decode step first.
The Dragonfly Black is in that latter class; it's an MQA renderer. When paired with an MQA-decode capable player, you get the full MQA result, and if not it will just play that content like a normal PCM file. You can easily tell when the Black is being fed decoded MQA content as the embossed Dragonfly on the unit will glow magenta. And you'll need to make sure your unit is running at least firmware version 1.06 for this to work!
One interesting aspect to DACs that only support MQA rendering, is that you can do back-to-back comparisons feeding them MQA content that has, or has not, been through the decoding phase - simply by turning that option off in your player. In doing this with the Dragonfly Black, it is relatively easy to discern that MQA content generally sounds better played with decoding enabled in your player thereby allowing the Dragonfly to do the final rendering step.
Specifics here include slightly improved transients, a better sense of air/space - particularly in acoustic pieces, an overall smoother sounding delivery - most notable in the upper registers and the "perception" of more detail/resolution. I say "perception" as I'm not convinced there's actually any more detail at all. It is quite common for what detail is present to be easier to hear if dynamic range is compressed - something MQA does (it uses the three least significant bits in the sample data for it's encoding, reducing the maximum dynamic range form 16-bits to 13-bits).
That's not to say it's always necessarily better than the equivalent non-MQA version of a track, assuming you can find otherwise identical MQA/non-MQA sources to compare. But again, it is relatively easy to tell the difference.
As of this writing, the Dragonfly Black is the cheapest MQA-renderer available and the Meridian Explorer 2 is the least expensive full-decoder (decoder + renderer).
Whether the feature is worthwhile at all, currently at least, depends a lot on where/how you get your music. While it's possible to buy MQA-encoded music from various vendors, by far the largest source of it is via TIDAL (you'll need a premium subscription and the desktop client - it's not currently supported by the web player or mobile clients). So unless you are, or plan to be, a TIDAL Premium subscriber MQA support is of questionable value currently.
The AudioQuest Dragonfly Black is a very cost-effective, high-quality, way to listen to both IEMs, and easier-to-drive full-size headphones. It’s raw performance is significantly better than the native output on any laptop or smart device that I’ve come across and, as such, represents an excellent upgrade to listening straight from such devices.
Not only does it typically deliver rather more power (2x-3x), but the quality of what is delivered is also distinctly better. Bass texture and articulation is significantly improved vs. the direct output on a MacBook Pro, resolution is better across the board, micro-dynamics become appropriately audible (often smoothed over entirely by built-in outputs), extension at both ends is superior and the overall presentation is smoother and more coherent.
It is small enough to take anywhere, works with pretty much any source from laptops to phones. And it’s inexpensive enough that it wouldn’t be crazy to buy one to leave in a laptop or headphone bag to ensure it was always available.
The common theme that emerges in listening to the Dragonfly Black across a variety of full-size headphones; that is making sure it is “paired with appropriate headphones”. This is mostly about power. The built-in amplification gives up the ghost aways before the limits of the DAC are reached. A surprisingly large number of well regarded headphones do fit within the capabilities of the Black’s drive capability.
If your headphones are in the sweet-spot, then this is a very satisfying and compelling little device and is easy to recommend. To the point that I can envisage a number of scenarios in which the Dragonfly Black is, perhaps, the only DAC/amp many listeners will need.
And if you’re an IEM user, which might be a more common use-case for a device like this, then power ceases to be a concern, and the low output impedance (important for most multi-BA-driver IEMs), combined with very low noise levels, makes it an even easier recommendation there.
-Ian Dunmore (@Torq)
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