Astell&Kern SR15 review: This digital audio player is packed with features and high-fidelity performance

Astell&Kern’s new SR15 hi-res digital audio player is built for those who have a passion for high-fidelity music on the go. Armed with Astell&Kern’s updated user interface, the ability to side-load a host of streaming services, a car mode, and lots more, you’ll be hard-pressed to find a better-built, more-flexible, or better-sounding player at this price point. 

The Astell&Kern’s SR15 (officially known as the A&norma SR15) is the first model from Astell&Kern’s new “standard” line of players. Astell&Kern says that the A&norma line is designed to “provide those new to high-resolution audio a feature-packed introduction to the Astell&Kern brand.” I’d say Astell&Kern succeeded in spades. 

Power and performance

The A&norma SR15 is the successor to A&K’s superb AK70 MK II that I previously reviewed. The SR15 is built for high-res music playback. Under the hood, you’ll find two Cirrus Logic CS43198 DACs performing the heavy lifting of converting digital audio files into the analog music you hear through your headphones. The SR15 will decode pretty much whatever file format you throw at it, including native support for 24bit/192kHz PCM audio and DSD64. 

The SR15 features a quad-core CPU. The powerful processor ensured a fairly fluid UI experience in my testing. I previously took Astell&Kern to task for the molasses-like UI response on their now discontinued AK Jr. Every subsequent A&K model I’ve reviewed has performed flawlessly.

The SR15’s feature list goes on with Wi-Fi, support for the AK Connect app (I’ll talk about this more below), USB DAC functionality, DLNA networking support, OTA (over-the-air) software updates, digital audio output via USB, and aptX HD.

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The SR15 has a new “car mode” that you can either switch on from the settings or add to the pull-down menu as a shortcut. When you enable car mode, it puts the interface full screen with large track-forward, previous-track, and play/pause buttons on screen similar to Apple Car Play. Car mode can be oriented either horizontally or verticaly. The SR15 is not compatible with Android Auto, in case you’re wondering.

Theo Nicolakis / IDG

For expansion, there’s a single microSD card slot that supports additional storage up to 2TB. The major feature, however, is support for Astell&Kern’s new Open App service that allows you to side-load a host of streaming music services onto the player.

Industrial design on display

Astell&Kern puts their industrial design prowess on full display with the SR15. The solid aluminum alloy body resembles the AK70 series, but takes on a unique flair. The screen is physically angled, tipping to the left like a leaning of Tower of Pisa. I must tell you it was really odd to get adjusted to the screen tilt when I first used the player. If you look at the photos throughout this review, you’ll see what I mean.

I presume they did because when you hold the player in your right hand, the display is parallel to your body. In other words you’re looking straight on to the screen. Visually it takes some getting used to for sure. Left-handed use is more awkward. The screen tilt is accentuated, and I found that I was tilting my head to look at the screen. I’m not a fan of this design decision.

Theo Nicolakis / IDG

The glass-covered rear panel has a 3D cube design that reminded me of the popular 1980’s video game Q-bert. The back panel shimmers as different sides of the 3D cubes pick up the light, alternating between diamonds and full 3D cube designs. It’s very cool and sophisticated.

I’ve had some A&K players with enclosures that had too-sharp edges; that’s not the case here. There’s an ever-so-slight bevel at every join that makes the player comfortable to hold. Thank you for listening A&K!

Built for wired and wireless lifestyles

The SR15 is designed for both wired and wireless listening. You’ll find a traditional 3.5mm headphone jack and a balanced 2.5mm output here, but the player also supports both aptX and aptX HD wireless headphones. AptX HD will stream high-res audio at bit rates up to 24-bits and sampling rates as high as 48kHz. You must have headphones that support aptX HD to get the best wireless performance, and the SR15 properly negotiated that connection with my B&W PX headphones. . 

Theo Nicolakis / IDG

The SR15’s entire enclosure acts as a giant heat sink. Generally speaking, the player remained cool; however, if I had it even a bit out in the sun, the player got very warm—almost hot to the touch. I’d urge caution before you tuck this baby into some pocket with little to no ventilation. 

Open App rocks, even if it’s clunky

The SR15 supports Astell&Kern’s new Open App feature. If you’ve used Astell&Kern players in the past, you know they typically support two, maybe three streaming services. That limitation is now gone. With Open App, you can install a wide variety of streaming services—including Apple Music.

Theo Nicolakis / IDG

Be prepared, however, for a clunky installation process. You must download the music service’s app to your computer, mount the player to your computer as a USB storage device, and then side-load the app onto the playere. Astell&Kern provides a complete step-by-step here. Astell&Kern needs to design a computer-free means of installing music services over a Wi-Fi network.

Loading Open Apps places them in a distinct section below the factory-installed Deezer and Tidal services. Once you’ve side-loaded any new apps, you’ll need to activate them.

Astell&Kern’s Open App also brings offline mode to services such as Tidal and Spotify. In the past, you couldn’t stream music from services such as these unless you were connected to a Wi-Fi network. I should note, however, that offline support is available only with the Open App versions. To get offline support for Tidal, for example, you must download and install the Open App version of Tidal in place of the version that’s on the player when you take it out of the box.

Theo Nicolakis / IDG

CD-ripping and streaming features

The SR15 will connect to Astell&Kern’s AK CD-Ripper for computer-less ripping of your CD collection. This feature has been a staple on the previous generation AK70 models. 

There’s no question that Astell&Kern has made a strong commitment to the shift towards streaming with Open App integration. But a hidden gem of the SR15 is the fact that it can serve as the heart of your music-streaming entertainment with AK Connect.

Theo Nicolakis / IDG

AK Connect leverages DLNA, so you can scan compatible DLNA servers for content, stream music from the SR15 to other DLNA-compatible devices, or use the player as a controller for content playback. Mount the SR15 to your computer as a USB storage device and scan its folders, and you’ll see that SR15 comes with a Mac and Windows DLNA-compatible media server.

The included MQS server will scan your computer for any music files and organize them by artist, album, genre, etc. Then, from the SR15, you can browse your music library over Wi-Fi anywhere in your house.The MQS Server won’t appear on your network, however, until it’s completely finished scanning and indexing your music files. This can take several minutes. Once indexing is complete you’ll see green light appear on the app’s interface, letting you know it’s ready.

Theo Nicolakis / IDG

Sweet Astell&Kern sound

I also paired the Astell&Kern SR15 with Focal Stellia closed back headphones using an Axios 2.5mm copper cable. For wireless listening, I used Bowers and Wilkins PX headphones. My observations below relate to the Focal Stellia pairing.

Simply put, the SR15’s sound is transparent, dynamic, and refined. Some might consider its sound a hair analytical. I’d say the sound is certainly in the same tradition of the AK70 MKII.

The SR15 doesn’t quite achieve the more velvety, smooth sound of Astell&Kern’s bulkier—and more expensive—KANN line of players. It’s not necessarily a bad tradeoff for ultra portability.

The SR15 had no problem driving the Focal Stellia headphones. The SR15 created a nice, layered soundstage with whatever music I threw at it. I reveled in Janos Starker’s performance of Bach’s Cello Suites, hearing every delicate stroke and the sense of space evident in the recording.

Microdynamics were a perennial strength. Turning on Pink Floyd’s Dark Side of the Moon or Sarah McLachlan’s Bloom Remix, I felt as though the SR15 revealed more of the nuanced elements of the mixes contained in the recordings. Listening to Sarah McLachlan’s “Ice (Dusted Mix)” or “Fumbling Towards Ecstasy (Junior Boys Mix),” I could clearly and distinctly make out each sound object perfectly layered in a three-dimensional space.

Theo Nicolakis / IDG

Listening to Saint-Saens Symphony No. 3 conducted by Carl Adam Landstrom, the SR15 and Focal Stellia one-two punch placed orchestral instruments firmly in space and time and gave me the ability to hear the very texture of each instrument.

Turning to more popular tunes, high-res recordings by Adele, Rebecca Pidgeon, Eric Clapton, and Steely Dan sounded pristine.

I do have a few critical observations: I wish that the SR15 had a bit more bottom-end oomph and dynamics. Bass was refined, but a bit shy on certain tracks I know well. I also find that the keyboard on such a small screen is difficult to navigate. I grew accustomed to making typos in user names, passwords, and searches. I’d like to see  larger screen real estate in a future upgrade.

Astell&Kern does it again

The SR15 is a superb, refined, high-res music player designed for the discerning music lover who doesn’t mind shelling out $699 for portable music bliss. Open App support is a real game changer for users who love Astell&Kern products, but have longed for either a broader selection of streaming services or offline/download support. If you have a previous generation AK70 or AK70 MKII, Open App alone makes the SR15 a worthwhile upgrade. Aside from the tilted screen, I loved my time with the SR15 and can’t recommend it strongly enough.