Review: Better High-Definition Audio From Your Smartphone

The DragonFly portable USB DACs and the Aumeo customizable headphone amplifier take HD audio to the next level

5 min read
Review: Better High-Definition Audio From Your Smartphone
Photo: Randi Klett

The modern smartphone may be a self-contained technological marvel, but that hasn't stopped engineers from coming up with a vast assortment of gadgets that plug into it. There are gizmos to augment your phone's camera, monitor your physiology, accept credit card payments, or even listen to software-defined radio. But the best of these (in my admittedly biased view) are the add-ons that improve the phone's music-playback capabilities. You can now get fantastic audio out of your phone—and you do not have to pay a lot to do it.

If you're an audiophile, you're probably aware of these offerings. But the dizzying array of products, promises, and prices may have left you puzzled. I'm here to help.

I spent some time recently with several intriguing new audio devices. The ones that stood out for me were the DragonFly Red (US $199) and Dragonfly Black ($99), which are digital-to-analog-converter headphone amplifiers from Audioquest in Irvine, Calif.; and the Aumeo, a $129 customizable audio device and headphone amplifier from Aumeo Audio in Hong Kong.

One pleasant surprise with these units is how tiny they are. The previous generation of portable digital-to-analog-converter (DAC) headphone amplifiers, for example, could be as big as a smartphone themselves. The DragonFly DACs, on the other hand, are the size of a flash-memory thumb drive.

But don't let that small size fool you. The DragonFlies are high-end, high-definition powerhouses that provide audio quality on a par with devices costing three or four times as much. They are known as USB DAC headphone amplifiers, because they plug into the USB port of your phone (or tablet or computer).

img AudioQuest.DragonFlyRed.MacAudiophile Solution: The DragonFly Red is a digital-to-analog converter and headphone amplifier that works with your smartphone, tablet, or laptop.Photo: Randi Klett

Before I describe the sound from these little powerhouses, some background is in order. Starting with Android 5.0 (Lollipop), late in 2014, Google finally accommodated long-suffering audiophiles by enabling the streaming of music data files directly out of the port. This freed music lovers from the DAC installed in the phone, which operates in the high-noise, electromagnetically challenging environment inside the phone. Google's decision was a big deal for audiophiles because unlike Apple's mobile devices, many Android phones have a slot for a microSD card, which can give you an extra 128 gigabytes. This is important because a single high-definition song stored in the popular Free Lossless Audio Codec, or FLAC, format can occupy anywhere from 6 to 195 megabytes, so even a modest music library would swamp the internal storage of today's smartphones.

To take advantage of the USB audio feature with your Android phone, all you need is an On-the-Go cable, which costs about $4, and a music media-player app that will play high-definition music files and direct the output to the USB port. That will set you back about $8. (iOS users can get the audio using Apple's camera adapter, which costs $40.)

To evaluate the Dragonfly models, I tried them with a variety of music files—orchestral, chamber music, jazz, and rock—and in formats ranging from MP3 to 24-bit/96-kHz FLAC. I also listened with four different headphones: the Audio-Technica IM70 earphones (retail price: $115); the NAD Viso HP50 ($249); the Audeze Sine ($449); and the Audeze EL8 Open-Back ($699). Those last two were made available graciously by Andrew Lorberbaum of Park Avenue Audio in New York City.

The DragonFlies can turn your Android smartphone into a bona fide, high-end audio machine. They will improve not just stored music but also streaming services such as Spotify and Google Play Music. But although the DragonFlies themselves are inexpensive by the standards of high-end audio, you will not derive much benefit from them if you are using budget earbuds. In my case, while listening through the relatively inexpensive Audio-Technica IM70s, I could not hear much difference between the DragonFlies and my Samsung Galaxy S5's internal DAC and amp.

But with the more costly headphones, the differences were quite apparent, becoming more so as I went up the cost spectrum. With the Audeze EL8s, the differences were stark: Bass notes were tighter and much more defined, percussion was sharper, and there were details and textures in vocals and strings that were simply not there with the internal DAC and amp. Listening with the Audeze EL8s to a recording of the Mozart clarinet quintet, I could close my eyes and visualize the cello as being to the right of the viola. Very rarely have I been able to perceive, with headphones and mobile gear, such a detailed soundstage.


imgPocket Size: The DragonFly Red DAC-headphone amp (top) and Aumeo (bottom) provide big sound from small packages.Photo: Randi Klett

Much more subtle were the differences between formats, sampling rates, and sample sizes. I could generally (but not always) hear a clear difference between MP3 and FLAC files. But my 54-year-old ears could hardly ever hear a difference between FLAC files at, say, 16-bit/44.1 kHz and 24-bit/96 kHz, even with the EL8s. So my suggestion is, if you own lots of CDs, load your microSD card with music ripped from them at 16-bit/44.1 kHz.

The Aumeo Audio device ($129) is something unique on the audio scene. To use it, you must first pair it with an app running on your iOS or Android device. The app plays a series of tones in eight different frequency bands. For each one—and for each ear—you adjust a dial on the app until you can barely hear the tone. In this way, the app determines the peculiarities of your hearing. With your hearing profile established, the device then compensates for those peculiarities, adjusting the power levels in each of the bands and for each of your ears. The profile is stored in the device, so once it's calibrated you can use it with different audio devices.

Besides the obvious aural benefit, the Aumeo also reduces the stress on your eardrums. Aumeo's literature suggests that people often instinctively increase the volume of their music so that they can hear details in frequency bands in which their hearing is weak. However, that means that they are overamplifying in the bands in which their hearing is strong. For some people, Aumeo claims, this overcompensation can contribute to “listening fatigue," which can manifest itself as a headachy feeling.

I am perhaps the ideal Aumeo customer. Three decades of scuba diving, and two injuries to my left eustachian tube, have left me with hearing that is idiosyncratic and asymmetric. And, indeed, I did find that the Aumeo let me listen to music more comfortably than I have in many years. With Aumeo, I had the odd and pleasurable sensation of listening to my favorite songs almost as if through young ears again.

If you are a music lover of a certain age and you often listen through headphones, the Aumeo can enhance your enjoyment. I do have a few minor quibbles with the device: it slightly exaggerates sibilance (i.e. the sound of the letter “s"). And when I used Bluetooth to pair it with my Samsung phone's music player, it would occasionally drop out for a fraction of a second during songs. However, I never have that problem when I connect to the Aumeo by means of a short cable, so that's how I use it now.

But my biggest beef with the Aumeo is that it is not widely available now. An initial offering through Indiegogo has sold out, and though the company has set up a waiting list for a second production round, no other details have been released.

Whether your ears are golden or olden, all these add-ons can take your listening to the next level. If you're an audiophile, the DragonFly Red is a compelling proposition, especially in comparison with stand-alone high-end audio devices such as the PonoPlayer and the Astell & Kern, which cost twice as much, and also require you to carry around another clunky gizmo. But even if you're just a music lover with decent headphones, the DragonFly Black is well worth auditioning. It differs from the Red model in its slightly lower power output and its analog, rather than digital, volume control. To my mind, at $99, it is one of the best bargains in high-end audio today.

This is an extended version of an article that appeared in the print edition as “DragonFly DACs."

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