AudioQuest DragonFly Cobalt USB D/A-headphone amplifier
- May 27, 2020
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Unlike the world of recorded music, where streaming has decimated sales of physical products, book publishing is seeing the reverse trend: sales of eBooks are declining while those of both hardback and paperback books are recovering. I have been a book junkie all my lifethe two long walls of my listening room are lined with floor-to-ceiling bookshelves and I have many boxes of books in storagebut these days almost all my book reading is with the Kindle app on my iPad mini.
Before I retired at the end of March 2019, most of my eBook consumption took place on the subway as I commuted to and from Stereophile‘s Manhattan office. But these days I settle down to my reading in my listening chair, with my iPad both running the Kindle app and allowing me to control what I am listening to with the Roon app. Mostly the music plays on the big rig, but I also listen on headphones, driving them with the AudioQuest DragonFly Red USB DAC that Art Dudley reviewed in September 2016, plugged into the iPad mini.
So when AudioQuest’s Stephen Mejias asked me a few months back if he could send me a review sample of the new DragonFly Cobalt, it took me less than a New York minute to say “Yes.”
. . . costs $299.95 compared with $199.95 for the DragonFly Red and $99.95 for the Black. What do you get for the extra coin?
All three DragonFlys feature Gordon Rankin’s StreamLength asynchronous USB code, which allows the DAC chip to control the conversion timing of the samples fed via the USB bus, reducing word-clock jitter. However, the Cobalt replaces the Red’s Microchip PIC32MX microcontroller with the new Microchip PIC32MX274, which is specified as increasing processing speed by 33% while drawing less current. While the Red’s DAC chip is the ESS Sabre 9016, the Cobalt uses ESS’s new ES9038Q2M DAC chip, which, like the earlier chip, incorporates a 64-step digital volume control. Like the DragonFly Red and Black, the Cobalt is limited to decoding data with a sample rate of 96kHz or lower. While the Cobalt’s reconstruction filter is still a minimum-phase type, the ultrasonic roll-off is slower, which AudioQuest says results in a more natural sound.
The Cobalt’s output amplifier is the same as that used in the Red, an ESS Sabre9601. This is a DC-coupled, unity-gain device and runs off a single positive voltage rail. (An integral charge pump provides the necessary negative voltage.) The Cobalt is also said to feature improved power-supply filtering, increasing the audio circuitry’s immunity to Wi-Fi, Bluetooth, and cellular noise.
Other than the color, the only external difference between the Cobalt and the Red is that the contoured enclosure is 10% smaller and doesn’t have the earlier DAC’s distinctive ridge above and behind the 3.5mm jack. As on the Red and Black, the DragonFly logo lights up in different colors to indicate status or sample rate: red for Standby mode; green for 44.1kHz data; blue for 48kHz; yellow for 88.2kHz (closer to lime green, I felt); light blue for 96kHz; and purple for MQA. AudioQuest warns that the DragonFly is an MQA renderer only and must be partnered with appropriate playback softwareRoon, for exampleto perform the first unfold with MQA files.
The Cobalt’s price includes a DragonTail USB-A (female) to USB-C (male) adaptor, for use with devices that have a USB-C port, like the iPad Pro.
For my initial listening sessions with the DragonFly Cobalt, I plugged it into one of the USB ports on my Roon Nucleus+ server. The Roon app recognized the Cobalt as an ALSA (Advanced Linux Sound Architecture) device, and I selected it as a playback zone and set it to render MQA files. I plugged a pair of AudioQuest NightHawk headphones into the DragonFly’s output jack and started playing music.
First up was my go-to performance of Bach’s Brandenburg Concerto No.6, with Richard Egarr directing the Academy of Ancient Music (24/88.2 ALAC files, Harmonia Mundi HMU 807461.62). The Cobalt clearly revealed the elaborate interplay between the two lead violas in the Concerto’s final movement without shining a spotlight on the sound. In fact, over the next few hours’ listening, it was the unfatiguing nature of the DragonFly Cobalt’s presentation that caught my attentionthat is, if a lack of something, digital glare and edge in this case, can call attention to itself.
I next called up “Rivers of Light” from the Portland State Chamber Choir performing works by Latvian composer Eriks Esenvalds (24/88.2 Qobuz stream from The Doors of Heaven, Naxos 8.579008). The work starts with a solo soprano singing a simple phrase over an ostinato jaw harp and descending choral “oohs” and “aahs” while the Cobalt is specified as being able to deliver a maximum output of 2.1V, this is into high impedances. When the Cobalt is required to drive lower impedances, the volume control has to be backed off to avoid clipping the DAC’s output amplifier. With the AudioQuest NightHawk until the full choir enters, singing of the glories of the aurora borealis. Again, the Cobalt and the NightHawks allowed me to hear deeply into the music without any unnatural emphasis. The warm reverb of Portland’s St. Stephen’s Catholic church, where I had made the recording, was presented around and behind the singers, though with the dark-sounding NightHawks, the reverb was overly warm.