Audioquest Dragonfly Cobalt

Hardware Review

Audioquest Dragonfly Cobalt
Friday, May 15, 2020
USB DAC/preamp/headphone amp
Richard Barclay

It’s hard to believe that it has been eight years since the release of Audioquest’s ingenious Dragonfly, the memory stick-sized USB DAC/preamp/headphone amp that provides a simple, effective and affordable solution to the problem of mediocre sound quality from computers. The original Dragonfly was supplanted in 2016 by two new models; the even more affordable Dragonfly Black, and the more expensive but also more powerful Dragonfly Red. Both featured redesigned USB controllers that drew a fraction of the current and made them compatible with not just laptops but also tablets and smartphones and, with two prices of admission, brought high quality sound to an even wider audience.

We now welcome the latest addition to the Dragonfly family, Cobalt. Retailing for £269, some £200 and £120 more expensive than the £69 Black and £149 Red, Cobalt becomes the new flagship in the series and is AQ’s most expensive and ambitious Dragonfly to date. Measuring just 57mm long (2 ¼”), the svelte new model is 10% smaller than its siblings and its streamlined profile and immaculate deep blue finish is more reminiscent of a finely polished jewel than a USB dongle.

Tech
While its size may have shrunk, Cobalt’s internals certainly haven’t been scrimped on. It sports the latest ES9038Q2M DAC chip from ESS that – like the ESS 9016 chip used in Red – has been implemented with a minimum-phase reconstruction filter. Unlike Red’s minimum-phase filter, however, AQ has chosen to roll-off ultrasonic frequencies less steeply in Cobalt to provide a “more natural sound”.

The new ’Fly retains Red’s ESS Sabre9601 amplifier output stage, but AQ has treated it to a new USB microcontroller, the Microchip PIC32MX274, which draws even less current and apparently increases processing speed by a third. Like previous models, Cobalt uses Gordon Rankin’s StreamLength asynchronous-transfer USB code. Its monoclock technology has a single, ultra-low jitter clock generated from the DAC chip that runs the ESS chip functions as well as all microcontroller functions.

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The built-in power supply filtering has also been upgraded, improving electrical noise rejection from wifi, Bluetooth and mobile phone signals to allow Cobalt to reach its full sonic potential. Rumoured to include elements from their successful Jitterbug USB noise filter, AQ evidently believes this upgrade to be of significant benefit as their previous advice to use a Jitterbug in series with Dragonfly Black and Red does not apply to their new flagship. (Listeners can however still use a Jitterbug in parallel, i.e. plugged into an unused USB port, if they wish to).

Hi-res
Free trials with Qobuz (1 month) and Roon (60 days) are included with the first 10,000 Cobalt units sold to whet your appetite for hi-res streaming. Cobalt supports native PCM sampling rates up to 96kHz at 24-bits and the Dragonfly logo illuminates accordingly to indicate the sampling rate of the file being played. It cleverly glows green for 44.1kHz content, blue for 48kHz, yellow for 88.2kHz, light blue for 96kHz and purple for MQA (note that Cobalt is an MQA renderer only and must be used with a player that can unfold MQA files). DSD is not supported natively so you need to configure the player to resample it to 88.2kHz PCM to preserve as much of the format’s qualities as possible.

Accessories
Cobalt is compatible with Apple and Windows computers, iOS and Android devices. Its bundled accessories include an engraved black leather storage pouch and a DragonTail USB adaptor, a short length of AQ Carbon USB cable that facilitates device connectivity whilst relieving port strain. AQ offers three DragonTail configurations: female USB-A to male USB-A, female USB-A to male microUSB/OTG, and female USB-A to male USB-C. Cobalt ships with the USB-C version but the others can be purchased separately for an additional £17.95. While the new iPad Pro features a USB-C port and can tethered using the included DragonTail, owners of Apple devices with Lightning ports must purchase either Apple’s Lightning-to-USB adaptor or the larger and more expensive Apple Lightning-to-USB 3 camera kit adaptor. AQ recommends the latter for superior sound quality and reliability. 

Like its 3.5mm TRS output-equipped Black and Red Dragonfly siblings, Cobalt can be used as a standalone DAC or as a DAC/preamp into headphones, powered speakers or a stereo power amp. It has a low-noise, 64-step bit-perfect digital volume control that can be controlled through either your source’s operating system or, where permitted, directly from within your preferred music player.

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Cobalt with Dragontail adaptor

Output power
When connected to a >10kΩ load such as an external preamp, power amp or active loudspeakers, Cobalt outputs a maximum of 2.1Vrms, comparable to many other line level sources. Despite an output impedance of just 0.65Ω, normally low enough for efficient power transfer and linear frequency response delivery into all but the most punishing of headphone loads, Cobalt’s maximum output voltage before clipping drops quite early on as load impedance decreases due to the output stage’s finite current supply. 

Unofficial measurements suggest Cobalt’s clipping point is -3dBFS with 300Ω ‘phones and -6dBFS with 30Ω ‘phones, output voltages of around 1.6Vrms and 1.05Vrms respectively. AQ recommends using headphones with an impedance no lower than 16Ω. Low impedance headphones tend to have higher voltage sensitivity and so usually require less output voltage than high impedance models to produce the same volume. The reduction in output voltage as load impedance decreases is therefore more likely to be an issue on the rarer occasions that Cobalt is paired with a low impedance headphone that also happens to have low sensitivity.

After putting the blue Dragonfly through its paces with headphones from 32Ω to 600Ω (see list at end of review), I recommend pairing it with low impedance ‘phones rated above 105dB/1Vrms or high impedance ‘phones rated above 102dB/1Vrms to ensure satisfyingly loud, distortion-free playback levels. As an over-ear headphones only listener I was unable to test the quietness of Cobalt’s residual noise floor with ear buds. However, no hiss was heard even through my most sensitive (117dB/1Vrms) over-ears, so I expect IEM wearers will be impressed by the blackness of Cobalt’s background.
My preferred source is a local NAS that contains a comprehensive library of standard- and high-res music, though I also venture onto Tidal to discover new content. Almost all listening takes place indoors, either in my living room/office which houses the main stereo and headphone systems, or in my bedroom where I have a second headphone system. As portability is one of Dragonfly’s key features, I also felt obliged to audition it in the great outdoors. Amidst the COVID-19 lockdown, this excitingly meant in my back garden with a MacBook Air over WiFi.

Vivid sound 
In both environments, AQ’s latest Dragonfly belies its tiny size and delivers a bold sound that is brimming with punch and detail. While both Black and especially Red already provide important steps up in quality from laptops’ and smartphones’ own headphone outputs, Cobalt widens the gulf further. Even when streaming Tidal in my garden against the sonic backdrop of cooing pigeons and purring lawnmowers, I couldn’t help but be drawn in by the clarity and completeness of the blue Dragonfly’s soundscape. 

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As excellent as its Red sibling is, it’s fair to say it is not always consistent in its delivery of bass and treble frequencies, which can be a little fuzzy and/or disjointed in places. Cobalt strips away this imprecision and presents a clearer and more cohesive image with seamless transitions between low, middle and high frequencies. Rhythm and timing are also improved; instrument fundamentals and overtones not only have more wholesome timbres but are also in closer lockstep and land with greater speed and impact. This is the most natural and vivid sound I have experienced from a USB DAC/headphone amp combo that offers such a high degree of portability and ease of use. It’s that good it may even trigger a change in listening habits by dissuading me from spending quite so much time listening indoors.

Speaking of which, having being impressed by its improvement over Red, I was curious to try Cobalt as a DAC in the main stereo system. Despite replacing a Schiit Yggdrasil that costs almost ten times as much and commandeers an entire shelf in the rack, the little blue Dragonfly did not embarrass itself. It may not be as nuanced as Yggdrasil, but its confident expression goes a long way to make up for what is otherwise lacking from the soundscape. 

Realising this was somewhat of a stacked fight, I decided it would be more relevant to see how Cobalt faired in my bedroom headphone system that is built around a book-sized Arcam irDAC-II DAC/preamp. In this setup the two were pretty much on a par with one another when driven within their limits, though if I had to declare a winner I’d most likely give it to the ’Fly for its slightly more punchy delivery. The book-sized, multi-input irDAC-II admittedly uses the much older ESS 9016 DAC chip, but I still find it remarkable that a comparable level of performance can now be obtained from a USB-powered dongle that isn’t much bigger in size than the DAC chip itself.

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Cobalt with Apple camera kit adaptor

Scaleability
Because a chain is only as strong as its weakest link, matching headphones to a source that’s a fraction of the price is an approach that is often frowned upon. It is however precisely for this reason, as a reviewer, that I make such pairings. High-end headphones can be extremely revealing of deficiencies upstream and therefore tell you a lot about the quality of the source. If there is any glare or edginess present in the treble response, for example, then headphones like the Audio-Technica ATH-ADX5000 or Sennheiser HD800S are sure to find it. While it may not be the best I’ve heard either of these two ’phones sound, Cobalt’s lack of grain provides a surprisingly smooth and insightful listening experience that should not dissuade you from partnering it with transparent headphones. 

Verdict
If you care about sound quality and listen to a lot of music on a laptop, tablet or smartphone, an Audioquest Dragonfly of any colour ought to be viewed as an essential purchase. All three models represent excellent value for money at their respective price points. However, if you want the most naturally cohesive and detailed listening experience, I do think it’s worth spending the extra on the flagship Cobalt. Even when listening casually the improvement is noticeable, and its smaller and more streamlined form factor makes it all the more easy to accommodate in an audiophile’s personal audio system.

Equipment used
Source/s: Mac Mini and MacBook Air running Audirvana+ and iTunes
Headphone/s: Audio-Technica ATH-MSR7/ATH-ADX5000, Beyerdynamic DT880, Focal Utopia, Sennheiser HD58X/HD600/HD800S
Stereo amplifier: Yamaha A-S3000
Loudspeakers: Celestion Ditton 66, Tannoy Monitor Gold 12
 

Specifications: 

Type: USB DAC, preamp, headphone amp
Sample rates (LED indicator color code): Standby (Red), 44.1kHz (Green), 48kHz (Blue), 88.2kHz (Yellow), 96kHz (Light Blue), MQA (Purple)
Volume Control: 64-position 64-bit bit-perfect
Output Voltage: 2.1 Vrms max
Headphone Amp: ESS Sabre 9601
DAC Chip: ESS ES9038Q2M with minimum-phase slow roll-off filter
Microcontroller: Microchip PIC32MX274
Dimensions (LxWxH): 57mm x 19mm x 12mm
Weight: 17g
Warranty: 2 years (Europe)

Price: 
£269
Manufacturer Details: