Name: Astell&Kern A&Ultima SP4000 | Digital Audio Player
Brand: Astell&Kern
SKU: AK-SP4000-BLK
Price: 4290.0 USD
Availability: InStock

Astell&Kern SP4000 DAP x3 rear black unit and front facing black and silver units turned inward whitebox

Astell&Kern SP4000 DAP black front center whitebox

Astell&Kern SP4000 DAP silver front center whitebox

Astell&Kern SP4000 DAP black rear center whitebox

Astell&Kern SP4000 DAP silver rear center whitebox

Astell&Kern SP4000 DAP black front rotated right 180 degrees whitebox

Astell&Kern SP4000 DAP silver front rotated right 180 degrees whitebox

Astell&Kern SP4000 DAP black rear rotated left 180 degrees whitebox

Astell&Kern SP4000 DAP silver rear rotated left 180 degrees whitebox

Astell&Kern SP4000 DAP silver front right 3 quarter angle in case whitebox

Astell&Kern SP4000 DAP silver rear left 3 quarter angle in case whitebox

Astell&Kern SP4000 DAP silver rear top left closeup of volume knob on black background

Astell&Kern SP4000 DAP front right 3 quarter angle standing on wooden table screen on with Astell&Kern Virtuoso headphones

$4,290.00

Color

Black

Silver

A&K's SP4000 Shatters the Limit Set by the SP3000, Harnessing Advanced Octa Circuitry to Deliver a Purer, More Powerful Sound Experience

Digital Audio Player with Snapdragon 6125 Octa-core processor
First Astell&Kern Device to Feature Advanced DAR Technology
Supports High Driving Mode for delivering premium sound quality
Ultra Low Noise LDO Regulator for top-tier noise suppression
Minimizes group delay with proprietary ESA (Enhanced Signal Alignment) technology

Astell&Kern SP4000 DAP standing rear right 3 quarter angle on black wooden stable with wood cabinet behind and vinyl record on one wall

Bloom's Take

Astell&Kern has always treated their flagship DAPs as a platform to redefine what’s possible in portable audio and with the SP4000, they’ve done it again. While it may not deliver the same leap forward that the SP3000 brought over the SP2000, the SP4000 feels like a culmination of every innovation that came before it, refined to its absolute limit.

The build quality is, as expected from A&K, sublime—equal parts futuristic and artisanal. Yes, it’s massive, yes, it’s heavy, and no, your pockets won’t thank you, but one listen and you’ll forget all that. Under the hood, the Quad-DAC setup, improved DAR processing, and High Driving Mode push its sonic performance into rarified territory. With IEMs or even challenging over-ear headphones, it delivers a vivid, expansive soundstage and a hyper-detailed yet cohesive image that feels more like a live performance than a playback.

Functionally, the SP4000 also marks a shift in Astell&Kern’s traditionally closed ecosystem. With Google Play preinstalled and true multitasking finally on board, the SP4000 softens the company’s “walled garden” approach and opens up to modern app use without compromising its player-first experience.

In the A&K lineup, the SP4000 doesn’t just sit at the top, it transcends it. While the SP3000 brought the revolution, the SP4000 perfects it. It’s not merely Astell&Kern’s best DAP yet, it’s the DAP to beat.

Read our full review.

Remarkably Close to Perfection

The A&ultima SP4000 is Astell&Kern’s newest flagship digital audio player, the result of three years of relentless research and innovation following the development of the SP3000.

Built upon an advanced Octa audio circuit architecture, the SP4000 distills the purest essence of audio engineering, delivering a sound experience unlike anything before it—refined, powerful, and remarkably close to perfection. Discover the SP4000 and experience sound on an entirely new level.

Snapdragon Octa-Core CPU

A&ultima SP4000 is equipped with a Snapdragon 6125 Octa-core processor, so you can enjoy the overwhelming sound, faster system response and a redesigned generation user interface that moves comfortably and smoothly. Featuring a high-performance CPU and improved 8GB of DDR4 memory, the more powerful system is stable with fast and fluid movement.

To maximize the efficiency of the circuit and reduce heat, the CPU, memory and wireless communication parts are configured as one module, with the digital circuit parts arranged in the same area creating a single system on a chip (SoC).

Astell&Kern SP4000 DAP lying face down rotated right 180 degrees on top of Audio-Technica Narukami tube amp

Enhanced Signal Processing with Octa Audio Circuit

In the SP3000, the digital-to-analog signal processing structure was separated in a 1:2 ratio. With the SP4000, it has evolved into a 1:1 architecture. This new structure, where one AK4191 digital processor is paired with one AK4499EX DAC, allows digital signals to be delivered precisely to a single DAC without the need to distribute noise, enabling improved signal separation and processing.

Through continuous research and innovation in circuit technology, the SP4000 successfully implements a true Quad DAC—a feat previously considered impossible due to noise and other issues. As a result, the SP4000 achieves an impressive SNR (Signal-to-Noise Ratio) of 131dB, on par with the independent dual audio circuit of its predecessor.

AstellKern SP4000 DAP Octa audio circuit architecture graphic

Advanced Engineering for Unmatched Clarity

High Driving Mode
The SP4000 features twice as many OPAMPs arranged in parallel compared to its predecessor, delivering richer and more detailed sound. High Driving Mode provides powerful and stable output—much like a four-wheel-drive vehicle confidently navigating rough terrain. It’s designed to reproduce even the most delicate sonic details with precision.

Enhanced Signal Alignment Technology
The SP4000 features proprietary ESA (Enhanced Signal Alignment) technology, which significantly improves one of audio’s long-standing challenges, group delay. ESA technology aligns frequency signals to arrive more uniformly, minimizing frequency distortion and dramatically enhancing sound clarity and purity.

Top-Tier Noise Suppression
The SP4000 features a newly implemented LDO (Low Dropout) Regulator in its power supply, which reduces noise by up to 97% compared to previous models. LDO Regulators help stabilize battery voltage and effectively suppress noise, resulting in cleaner, purer sound.

Precision Sound with Any Layer HDI PCB
To minimize signal loss, the SP4000 incorporates top-tier Any Layer HDI (High-Density Interconnect) PCB technology. Commonly used in smartphones and high-performance electronic devices, this advanced circuit board allows for the precise design of complex circuitry within a compact space.

AstellKern SP4000 DAP x4 closeup images of stainless steel body and volume wheel

Additional Features and Enhancements

Sound Design Through DAC Filters
With the SP4000, you can enjoy the fun of creating your own sound style by directly selecting various DAC filters provided by the DAC manufacturer. Design your own sound through 6 DAC filters.

4.5th Generation UI
The SP4000 features an upgraded UI that balances both functionality and emotional experience.

A&K's First Full Android OS Integration
Astell&Kern has overcome Android OS’s sampling limitation (SRC) through its proprietary customization technology, ADP (Astell&Kern Direct Path).

First-Ever Implementation of Advanced DAR by Astell&Kern
The SP4000 introduces Advanced DAR, Astell&Kern’s second-generation DAR (Digital Audio Remaster) technology, delivering sound that is even more natural and refined.

AstellKern SP4000 DAP digital audio remaster second generation graphic

99.9% Pure Copper Shield Can
For the first time in A&K's lineup, the SP4000 is equipped with a precision-engineered Shield Can to block various types of noise and electromagnetic interference that could affect the audio block.

6-inch 2K Display
Experience the SP4000 more conveniently and comfortably with a wide 6-inch, large-screen 2180x1080 2K display.

AK File Drop
With the new AK File Drop function in the SP4000, you can freely transfer files wirelessly through a PC, smartphone, or FTP program located on the same network

Automatic 'ReplayGain' and Uniform Volume Adjust
ReplayGain adjusts sound sources with different volumes to identical levels so you can enjoy your own playlists seamlessly.

Wireless Hi-Fi Sound via BT Sink
Enjoy playback from an external device (ie. smartphone) in high-quality using the BT Sink function.

PD 3.0 Fast Charging Supported
The SP4000 supports Qualcomm QC 3.0 fast charging, so you can charge your DAP faster and more efficiently than previous models, reaching a full charge in about 4 hours.

Crossfeed Technology
Through the use of detailed settings such as Shelf Cutoff, Shelf Gain, and Mixer Level, you can set the level of crossfeed according to your listening preferences.

Material Innovations
The SP4000 uses 904L stainless steel material that has never been attempted before in a portable audio player. Using this material has expanded its value from just a digital device to the realm of a luxury good.

Shrunken Calfskin Leather Case
The SP4000 comes with a deluxe case crafted from shrunken calf leather sourced from Perlinger in Germany, ensuring a level of style and quality that matches the quality of the device.

AstellKern SP4000 standing back left 3 quarter angle with leather case

Specifications

Full list of specifications
Astell&Kern 1 Year Warranty

In the Box

A&Ultima SP4000 DAP
Premium German leather case
USB-C cable
Quickstart guide

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The a&k sp4000

Bloom Audio is a very professional audio company and the Astell&Kern SP4000 is the best DAP on the planet. Thank you, Bloom.

SP4000 <-- waay better than SP3000

Just upgraded from SP3000 to SP4000.
It is super neutral, but extremely high resolution in High-driving mode, little things you haven't heard before in well known tracks.
DACs are still Asahi Kasei from Japan, some of the best delta sigma's around.
Filter setting add one new setting 'low dispersion' mode which improves sound coherence.
The clarity, separation, dynamic range, and suitable for both analytical and emotive listening.
I paired this device with the Empire Ears Odin & 64 Audio Fourte Blanc.
This device is heavier than my SP3000, the setup is very similar to the SP3000, save that the power button seems to have a much better tactile response, and doesn't feel 'squishy' like the SP3000 Volume button. This one also has a button lock switch, a most welcome addition as the buttons on these DAPS are sensitive.
UI is snappy, slightly upgraded from the SP3000T and SE300 UI.
WIFI through roon is spectacular.
USB DAC mode is spectacular.
Blue Tooth has many more options than even the SP3000 DAP, to improve the sound quality through various modes, and the latest ones too.
Storage is the same as always, 256gb ssd, with up to 1TB micro SD card slot. I have a 1TB card from my old SP3000, and its never even been used because all my song collection is smaller than 256gb.
Final thoughts: is it worth the price tag? It is for me. For those of use who enjoy Astell&Kern products this is one you don't want to miss.
Thanks Bloom Audio, I preordered this and it still came super quick.

Very quiet DAP

This is a preliminary review , since I cannot use the balanced mode.
Compared to my A&K SP3000 this 4000 unit is noticeably quieter. I exclusively listen to cd rips and 24bit 192khz vinyl transfers and the music is predominately orchestral, big band,large jazz combos , some jazz trios .
The iems are Final A8000.
I can use them balanced with the SP3000, but not so with the 4000. I tried a Geekria 2.5mm to 4.4mm converter but this resulted in a sound that was inferior to the SP3000.
This converter seemed to exaggerate the ill defined bass and much of the quietness introduced by the SP4000 disappeared.
Using the 4000 single-ended,unbalanced with the Final8000 was engrossing and time spent listening passed quickly,however the bass was more than the 3000 , bordering on too much and not as controlled.
I believe the new iem I shall be getting: Final A10000, which I can use balanced 4.4mm and is known for its extremely low bass distortion and control will show the full potential of the 4000.
Note: the DAR is very useful ,PCM setting, and preferred on those recordings that most likely were made in the Dolby era. But those made in an earlier era , it was a toss-up as to whether it was a net positive.

Perfect Imperfection

If you know your DAPs, done your research and know what imperfections to expect, it’s a solid 5/5. I haven’t been able to put this thing down for 2 days.

Those imperfections do still exist though. I love the weight and size, but it doesn’t provide more playtime nor less heating. The actual playtime is about 6 hours and the heating after 1 hours of playing is concerning.

The software also needs more work, it can’t decode some of my tracks that my other devices are fine with. And just having those tracks in the storage will disrupt and crash the player process. I had to go through the hundreds of tracks in my collection and delete all the ones it can’t decode, to make sure it wouldn’t constantly tripping on them.

But I loved every bit of the sound came from it. It’s like rediscovering some of my old favorites.

I upgraded from a midrange DX260, which is much more user friendly. But in terms of sound quality and build quality, the SP4000 is hard to pass.

DAP if you don't have one get the best one!

I come from a generation of boom box, living room stereo system, the original iPod, I was part of the a/v club in high-school, and I work with musicians for live concerts. I did my research before I bought the A&K sp4000. Initially I was gonna purchase the sp3000, but the 4 was out so here i was. I was just looking to replace my broken 256gb iPod when a friend of mine introduced me to a DAP she had a HiBi I believe from Amazon and it looked good, but it got me curious since I've been listening to streaming service for so long and I hate not being able to listen without internet connection or losing my Playlist or collection because either I stop paying or the service loses there license from the publisher. Plus I wanted hi-res audio and all my collection in 1 device with no interruption from phone calls or other distractions. I've got to say DAP's are the answer, and A&K did a phenomenal job. The sound quality that I get vs. my phone or my iPad is apples to oranges. It brought me back to my old 90's house home system sound quality. It's so crisp. You can hear every detail to the sound with no distortion. I have a bose in ear quiet comfort ultra as well and using it with the A&K is so much more different. Direct hookup to the seinhesser I bought with these are amazing. I'm telling you guys right now if you're a music lover like me, and it doesn't matter the type, classical, r&b, rap, country, pop, rock, and or hip- hop in general! Switch to a DAP. This A&K sp4000 is pretty much the latest and greatest and if money is no option this is the one im gonna say to get. My only gripe with this thing is it's heavy, but it is so beautiful to look at. I also wish it was running the latest Android os or it had support from Google to be able to update to the latest android os hence the 4 star. Other than that A&K keep up the good work. Bloom Audio, THANK YOU! For the wonderful service and my new beautiful Astell & Kern sp4000. I am very positive you just earned a happy returning customer in the future!

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Astell&Kern A&Ultima SP4000 | Digital Audio Player