Astell&Kern A&ultima SP4000 Digital Audio Player

A&ultima SP4000 Digital Audio Player, by Astell&Kern.

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.

A&ultima; SP4000 Video

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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 131 dB, on par with the independent dual audio circuit of its predecessor.

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, allowing you to enjoy deeper, clearer, and more immersive music.

Top-Tier Noise Suppression + Any Layer HDI

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 are high-performance components typically used in precision medical devices and 5G communication equipment. They help stabilize battery voltage and effectively suppress noise, resulting in cleaner, purer sound.

In addition, to achieve the highest sound quality, 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. It minimizes signal loss, enabling the delivery of a more refined and detailed sound.

Full Android OS Integration

Astell&Kern have overcome Android OS’s sampling limitation (SRC) through their proprietary customization technology, ADP (Astell&Kern Direct Path). This allows for bit-perfect, lossless playback even in streaming environments, ensuring the highest possible sound quality during music listening.

Features

• 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.
• Real-time LED lighting information.

Specifications

• Model: SP4000
• Body Colour: Black, Silver, Copper
• Body Material: Stainless Steel 904L
• Display: Full 2K 6-inch 2016 x 1080 Touch display
• Supported Audio Formats: WAV, FLAC, WMA, MP3, OGG, APE, AAC, ALAC, AIFF, DFF, DSF
• Sample Rate: PCM 8 kHz - 768 kHz (8/16/24/32-bits per Sample), DSD Native DSD64 (1-bit, 2.8 MHz), Stereo / DSD128 (1-bit, 5.6 MHz), Stereo / DSD256 (1-bit, 11.2 MHz), Stereo / DSD512 (1-bit, 22.4 MHz), Stereo
• Output Level: Unbalanced 4.1 Vrms / Balanced 8.2 Vrms (Condition No Load)
• CPU: Octa-Core
• DAC: AKM4191 x4 + AKM4499EX x4 (Real Quad-DAC)
• Decoding: Support up to 32-bit / 768 kHz Bit-to-Bit Playback
• Input: USB Type-C input (for charging, PC + MAC)
• Outputs: Unbalanced Out (3.5 mm) / Optical Out (3.5 mm) / Balanced Out (4.4 mm, only 5-pole supported)
• Wi-Fi: 802.11 a/b/g/n/ac (2.4/5 GHz)
• Bluetooth: V5.0 (A2DP, AVRCP, Qualcomm® aptX™ HD, LDAC, SBC, AAC)
• Dimensions W x H x D: 85 x 149.8 x 19.5 mm
• Weight: About 615 g
• Feature Enhancements: Firmware upgrade supported (OTA)
• 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
• Signal to Noise Ratio: 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)
• Clock Jitter: 25 ps (Typ)
• Reference Clock Jitter: 200 Femto Seconds
• Capacity: 6780 mAh 3.8 V Li-Polymer Battery
• Playback Time: About 10 hours (Standard: FLAC, 16-bit/44.1 kHz, Vol. 50, LCD off)
• Charge Time: About 5 hours (QC 3.0 Charging)
• Built-In Memory: 256 GB [NAND]
• External Memory: microSD (Max. 1.5 TB) x 1
• Supported OS: Windows 10, 11 (32/64 bit), MAC OS X 10.7 and up

Included

• 1 x A&ultima SP4000 Player
• 1 x Leather Case
• 1 x USB-C Cable
• 1 x Accessories & Documentation

More Information

• A&ultima SP4000 DAP, by Astell&Kern