There’s very little in the portable audio world that comes anywhere close to the complete package of an Astell&Kern flagship DAP. The design, material selection, and build are always incredible, and the level of sound quality and audio precision is every bit as good as the build. The SP3000 elevated the material and sound quality over the SP2000 while delivering a whole new user interface, and while the SP4000 doesn’t represent as much of a leap over the SP3000, there are a lot of details that make it just as significant a step forward.
Build and Design
At first glance, the SP4000 is basically a bigger SP3000, but there’s more to the exterior design than a new screen. The SP4000 adds a control lock switch on the top to prevent accidental volume changes or track switches while the device is in your pocket, and it upgrades the internals with an improved processor, more memory, and an updated Quad-DAC design (full specs here). The general feel of the SP4000 is incredible: this thing looks and feels more like a spaceship component from the 22nd century than a simple music player.
The SP4000 weighs 21.7 ounces. Combine that with a 6-inch screen and the extra girth needed for the audiophile components, and your pockets are in for quite the workout. This is far from the most pocketable player in Astell&Kern’s lineup and even pushes the edge of portability. The SP4000 certainly can travel with you, but the size and weight mean that it’s more comfortable resting on a desk or an end table than in your pocket
Using the SP4000
While the improvements to device performance and sound quality are quite noticeable, the biggest difference the SP4000 brings is that it lowers the walls a bit on Astell&Kern’s “walled garden” style device OS. While you still boot into the Crimson UI, with its very much player-first design, the App Drawer has the Google Play Store preinstalled, allowing you to sign in and download any app you want.
While you can download the full selection of apps, it’s not guaranteed that every app will work. The standard apps like Qobuz, TIDAL, Spotify, and the like all work great, along with a selection of other music apps and players, like SoundCloud and Bandcamp. Outside of music apps, it was more of a mixed bag. Netflix downloaded but was unable to start, while TikTok and Clash Royale ran perfectly. It will be nearly impossible to create an exhaustive list, but if additional apps are a “nice to have” and not a requirement, there will be plenty of extras you can install to make your player more of a complete multimedia device than past Astell&Kern players.
The addition of more app options led Astell&Kern to also boost the multitasking capabilities of the device, and they’ve implemented a button in the UI to easily view the apps that are currently running and swap between them. The device also provides better general performance than any Astell&Kern device yet, meaning that running multiple apps and swapping between them is fast and smooth. Another nice addition to the UI is a button on the bottom menu that switches to a VU meter. The VU view is a nice visualization when you’re playing music.
Ultimately, the goal here isn’t playing Clash of Clans or having the smoothest app switching, but instead delivering flagship-level sound quality. The SP4000 carries on features from its predecessors, like Parametric EQ (the EQ works system-wide, even inside of apps) and Crossfeed, while improving the Digital Audio Remaster (DAR) feature and adding High Driving Mode, which better optimizes the output for hard-to-drive headphones. So what’s the final result?
Sound
What most audiophiles are pursuing in their audio stacks is an idealized version of capturing what “live music” sounds like. To achieve this, a stack needs to deliver a realistic sense of stereo imaging, with a clear sense of space and positioning of sound within that space, a realistic timbre and weight to instruments and voices, and clear details—all with an energetic, impactful presentation. I’ve never experienced a single unit that can provide all of that the way the SP4000 does.
Listening with a variety of mid-tier through flagship IEMs, the SP4000 delivered a wide soundstage and imaging that seemed to function on two separate levels: on one level, there was crystal-clear separation and definition between each voice and instrument, while on the other, there was a strong sense of cohesion and blending between and around the instruments. Whether you’re dealing with a highly refined multi-BA IEM like the Noble Ronin, an insanely technical quad-brid like the Empire Ears Raven, or something simpler like the Campfire Audio Clara, the SP4000 delivers a masterful audio presentation.
While the SP4000 is still at its best with IEMs, the new High Driving Mode notably steps up its capabilities with over-ear headphones. While the Astell&Kern KANN Ultra—being specifically designed with headphones in mind—has more wattage output, I actually preferred the overall sound quality and dynamics of the SP4000 using High Driving Mode with some harder-to-drive headphones like the HIFIMAN Susvara Unveiled and DCA E3.
Comparison: Astell&Kern SP3000M, iBasso DX340
Probably the closest comparison at the moment to the SP4000 is the third iteration of its predecessor: the SP3000M. Another potential option is the iBasso DX340, which comes in at half the price but represents iBasso’s most refined flagship yet. Let’s look at the features, design, and audio performance to see how these three stack up.
In terms of design, the SP4000 definitely takes the cake as the most beautiful audio player you’ve ever seen—but without the case, it can feel a little ostentatious and impractical, given how quickly it picks up smudges and fingerprints. The DX340 doesn’t have quite the same visual or tactile appeal as the SP4000, but it’s smaller, lighter, and fits in your pocket a bit more easily. The SP3000M compares well here, with a touch of the visual flair and impressive material design of the SP4000, but with a more reserved look and a much more pocketable form factor.
In terms of device features, the DX340 is going to easily win this one with its full Android 13, swappable amp cards, and all that, but the SP4000’s audio-specific features might give it a slight edge over the DX340. The improved DAR makes it an even bigger standout for the way it improves the quality of some of my older lossy CD rips, making them sound notably better than they did on the DX340. The EQ features that apply across the full system—and not just for the player—are a big deal as well. The SP3000M lags behind here, providing an older version of DAR and more limited app functionality.
In isolation, all three sound amazing, offering an incredible blend of accuracy, detail, and musicality, but the SP4000 clearly stands out among the competition. Compared with the SP3000M, the stage is wider and deeper, and the dynamics are stronger and harder-hitting. The same is true compared to the DX340, where the SP4000 also feels more detailed and more precise in its timing and transient attack. One place the DX340 stands out is with its direct DC input mode, where it’s able to provide performance with over-ear headphones that exceeds the SP4000’s High Driving Mode.
The Bottom Line
When the SP3000 hit the market, it was, to my ears, the best player available, and it represented a leap forward for Astell&Kern’s UI and design. As the next flagship player, the SP4000 has a lot to live up to, and it largely exceeds expectations—especially in terms of its sound and UI improvements. The size and weight may be too much for some listeners, but the pure sonic bliss that the SP4000 delivers overshadows its predecessors and once again puts Astell&Kern on top in the DAP world.
