*Call store for details*
 
Built on Legacy, Evolving 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.

As part of the A&ultima series—Astell&Kern’s flagship lineup combining cutting-edge technology and top-tier specifications—the SP4000 surpasses the boundaries set by the SP3000, once regarded as the ultimate reference.

Built upon an advanced Octa audio circuit architecture, the SP4000 distils 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. 
 
Enhanced signal processing capabilities with Octa audio circuit architecture
Supports High Driving Mode for delivering premium sound quality
Minimizes group delay with proprietary ESA (Enhanced Signal Alignment) technology
Ultra Low Noise LDO Regulator for top-tier noise suppression
Precision sound achieved with Any Layer Type PCB
Equipped with a 99.9% Pure Copper Shield Can
First Astell&Kern Device to Support Full Android OS
First Astell&Kern Device to Feature Advanced DAR Technology
Features 4.5th generation UI, combining functionality and emotional design
 
Enhanced Signal Processing Capabilities with Octa Audio Circuit Architecture
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.
 
Supports High Driving Mode for Premium Sound Performance
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, allowing you to enjoy deeper, clearer, and more immersive music.
 
General Specifications
Model 
SP4000 (PPF51)
Body Color 
Black, Silver
Body Material 
Stainless Steel 904L
Display 
6inch 2K (2160 x 1080) touch screen
Supported Audio Formats 
WAV, FLAC, WMA, MP3, OGG, APE, AAC, ALAC, AIFF, DFF, DSF
Sample rate 
PCM : 8kHz ~ 768kHz (8/16/24/32bits per Sample)
DSD Native : DSD64(1bit 2.8MHz), Stereo | DSD128(1bit 5.6MHz), Stereo
DSD256(1bit 11.2MHz), Stereo | DSD512(1bit 22.4MHz), Stereo
Output Level 
Unbalanced 4.1Vrms │ Balanced 8.2Vrms (Condition No Load)
CPU 
Octa-core
DAC 
AKM4191 x4 + AKM4499EX x4 (Real Quad DAC)
Decoding 
Support up to 32bit / 768kHz Bit to Bit playback
Input 
USB Type-C input (for charging & PC & MAC)
Outputs 
Unbalanced Out (3.5mm), Optical Out(3.5mm)
Balanced Out (4.4mm, only 5-pole supported)
Wi-Fi 
802.11 a/b/g/n/ac (2.4/5GHz)
Bluetooth 
V5.0 (A2DP, AVRCP, Qualcomm® aptX™ HD, LDAC, LHDC, SBC, AAC)
Dimensions 
3.34” (85mm)[W] x 5.89” (149.8mm)[H] x 0.76” (19.5mm)[D]
Weight 
About 21.7oz (615g)
Feature Enhancements 
Firmware upgrade supported (OTA)
Operating Temperature 
0℃ ~ + 40℃ (32℉~ 104℉)
 
Audio Specifications
Frequency Response 
±0.006dB (Condition : 20Hz~20kHz) Unbalanced │ ±0.006dB (Condition : 20Hz~20kHz) Balanced±0.06dB (Condition : 20Hz~70kHz) Unbalanced │ ±0.06dB (Condition : 20Hz~70kHz) Balanced
S/N 
129dB @ 1kHz, Unbalanced │ 131dB @ 1kHz, Balanced
Crosstalk 
-136dB @ 1kHz, Unbalanced │ -145dB @ 1kHz, Balanced
THD+N 
0.0005% @ 1kHz, Unbalanced │ 0.0003% @ 1kHz, Balanced
IMD SMPTE 
0.0004% 800Hz 10kHz (4:1) Unbalanced │Balanced
Output Impedance 
Unbalanced Out 3.5mm (0.7ohm) │ Balanced Out 4.4mm(1.7ohm)
*Audio measurements are based on the Normal mode.
*Auto Mute is not used during audio testing.