Astell&Kern SP4000 silver

The SP4000 from Astell&Kern is a high-end audiophile player. Developed over three years following the SP3000, it introduces a unique Quad DAC architecture to the lineup, full integration of Android OS, and premium materials. Its chassis is made of stainless steel, and its ceramic back features a PVD treatment. This model incorporates several proprietary technologies and is aimed at users seeking a portable device with extended audio performance and meticulous craftsmanship.

Revolutionary Audio Architecture

At the heart of the SP4000 lies an Octa audio circuit architecture with a true Quad DAC, marking a major technical breakthrough. Unlike the SP3000, which used a 1:2 ratio between digital processors and converters, the SP4000 adopts a 1:1 architecture where each AK4191 processor is directly paired with a dedicated AK4499EX DAC. This configuration eliminates the noise distribution inherent in shared architectures and achieves an exceptional signal-to-noise ratio of 131dB.

The parallel configuration of operational amplifiers is another significant innovation. The High Driving mode leverages this architecture to deliver remarkable output levels, using twice as many operational amplifiers as the SP3000. This approach ensures precise reproduction of the subtlest details while maintaining outstanding dynamics, creating a denser and more powerful sound.

Signal processing with four sophisticated AK4191 digital processors and four AK4499EX DACs enables precise signal transmission with drastically reduced noise levels. This architecture minimizes signal loss and optimizes channel separation.

First Audiophile Android OS

The SP4000 marks Astell&Kern’s entry into the modern streaming era with full integration of Android OS. This revolution allows access to the Google Play Store and installation of third-party apps like Tidal, Qobuz, Spotify, or Apple Music. The proprietary ADP (Astell&Kern Direct Path) technology bypasses Android’s resampling limitations, ensuring bit-perfect playback even when streaming.

This Android implementation remains optimized for audio with a specially designed 4.5th generation user interface. The 6-inch 2K touchscreen displays smooth animations when browsing music collections, maintaining Astell&Kern’s recognizable visual identity.

The Snapdragon Octa-Core processor, supported by 8GB of DDR4 memory, ensures exemplary responsiveness. The system-on-chip architecture integrates CPU, memory, and wireless communication components into a single module, optimizing energy efficiency.

Exceptional Materials and Construction

The SP4000 debuts the use of 904L stainless steel in portable audio, a material previously reserved for luxury watchmaking. This premium construction is complemented by a PVD-treated (Physical Vapor Deposition) ceramic back, offering exceptional scratch resistance and refined aesthetics.

The device is protected by a Perlinger leather case, crafted by renowned German artisans known for their cold-tanning techniques. This process preserves the leather’s natural patterns while allowing for deep coloring that will develop a unique patina over time.

Electromagnetic shielding reaches an unprecedented level with a Shield Can made of 99.9% pure copper. This precision metal protection effectively blocks electromagnetic interference that could affect audio circuits—a first in the Astell&Kern lineup.

Proprietary Technologies

ESA (Enhanced Signal Alignment) technology tackles the persistent challenge of group delay in digital audio. This phenomenon, where different frequencies travel at varying speeds through circuits, can affect temporal accuracy. ESA synchronizes the arrival of frequency signals, minimizing distortion and improving frequency coherence.

The SP4000 introduces next-generation Advanced DAR (Digital Audio Remaster). Thanks to advanced upsampling, this technology recovers harmonics often lost during digital processing, delivering unmatched finesse. This process restores lost harmonics and uses more powerful oversampling to bring refinement and naturalness to music.

The ultra-low noise LDO (Low Dropout) regulator represents a significant advance in audio power supply. Borrowed from precision medical equipment and 5G communication systems, this component reduces power supply noise by 97% compared to previous models.

Modern Connectivity and Versatility

The SP4000 features extensive connectivity with dual-band Wi-Fi and DLNA compatibility for network streaming. Bluetooth 5.0 supports high-quality aptX Adaptive and LDAC codecs for 24-bit audio transmission.

A notable innovation is the intelligent BT Sink function, allowing the SP4000 to operate as a wireless DAC. This feature transforms the player into a Bluetooth receiver capable of connecting to external sources such as a PC/Mac, meeting the needs of high-end audio setups.

Roon Ready certification is being finalized following testing and certification by Roon Labs. This compatibility will further expand integration possibilities within modern digital audio ecosystems.

Sound Performance and Storage

The SP4000 natively supports high-resolution PCM files up to 32-bit/768 kHz as well as DSD512 (22.4 MHz). This ultra-high-resolution compatibility far exceeds current standards and those of many competitors.

Generous storage starts with 256 GB of internal memory, expandable up to 1.5 terabytes via microSD card. This capacity allows you to build and carry a substantial music library without compromising file quality.

Optimized battery life offers up to 10 hours of continuous playback, with a full recharge in just 4 hours thanks to Qualcomm QC 3.0 technology. This endurance meets the demands of extended listening sessions.

Frequently Asked Questions

What is the main difference between the SP4000 and the SP3000?
The main evolution lies in the 1:1 architecture replacing the SP3000’s 1:2 ratio, eliminating noise distribution. Full Android integration with ADP revolutionizes daily use, while materials advance to 904L steel and PVD ceramic. The SP4000 also uses twice as many operational amplifiers for a denser, more powerful sound.

Is the BT Sink function really useful in practice?
This feature transforms the SP4000 into a reference wireless DAC, instantly improving the audio quality of external sources like a computer. For high-end audio setups, it avoids the need for a dedicated DAC while preserving Astell&Kern’s signature sound.

Does full Android affect audio performance?
ADP (Astell&Kern Direct Path) technology elegantly bypasses Android’s resampling limitations, ensuring bit-perfect playback even when streaming. This proprietary solution preserves audiophile quality while providing access to modern apps.

Do the materials really justify the high price?
904L steel used in luxury watchmaking, PVD ceramic, and the Perlinger case represent an exceptional level of finish. These materials offer durability, corrosion resistance, and optimized vibration properties, justifying a positioning comparable to prestige watches.

What is the actual battery life with intensive use?
The stated 10 hours correspond to optimized continuous playback. With mixed use—streaming, browsing, and active screen—battery life may decrease but remains competitive thanks to the optimized Snapdragon processor and 4-hour fast charging.

Is the 615g weight acceptable for portable use?
Astell&Kern accepts this size/performance trade-off, aiming for technical excellence over compactness. This approach suits users who prioritize absolute quality, similar to professional cameras where bulk is accepted for performance.

Will Roon Ready certification be available at launch?
Roon Ready certification is being finalized after testing by Roon Labs. This compatibility should be available soon after launch, expanding integration possibilities within digital audio ecosystems.

Can the SP4000 replace a home audio system?
With its BT Sink function, balanced and unbalanced outputs, and high driving capability, the SP4000 can indeed serve as a reference source for a home system. Its versatility makes it a central audio hub for modern audiophiles.

Technical Specifications

Architecture and Audio Processing

• Octa audio circuit architecture with enhanced signal processing capabilities
• High-power mode for premium sound quality
• Reduced group delay thanks to proprietary ESA technology
• Ultra-low noise LDO regulator for optimal interference suppression
• Sound precision achieved with a multilayer printed circuit board
• Equipped with 99.9% pure copper shielding
• Advanced DAR (Digital Audio Remaster) technology
• 4.5th generation user interface, combining functionality and emotional design

Converters and Decoding

• Processor: octa-core
• DAC: AKM4191 x4 + AKM4499EX x4 (true quad DAC)
• Decoding: supports up to 32-bit / 768 kHz in bit-perfect playback
• Output levels: unbalanced 4.1 V RMS, balanced 8.2 V RMS (no-load condition)

Audio Formats and Compatibility

• Supported audio formats: WAV, FLAC, WMA, MP3, OGG, APE, AAC, ALAC, AIFF, DFF, DSF
• Sampling rates:
  • PCM: 8 kHz to 768 kHz (8 / 16 / 24 / 32 bits per sample)
  • Native DSD: 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

Connectivity and Interfaces

• Input: USB Type-C (for charging and PC / Mac connection)
• Outputs:
  • unbalanced output (3.5 mm)
  • optical output (3.5 mm)
  • balanced output (4.4 mm, 5-pole support only)
• Wi-Fi: 802.11 a / b / g / n / ac (2.4 / 5 GHz)
• Bluetooth: V5.0 (A2DP, AVRCP, Qualcomm aptX HD, LDAC, LHDC, SBC, AAC)

Display and User Interface

• Display: 15.2 cm 2K (2160 x 1080) touchscreen
• First Astell&Kern device to support the full Android system
• Access to Google Play Store and compatibility with third-party audio apps

Storage and Memory

• Internal memory: 256 GB
• microSD expansion: up to 1.5 TB
• DLNA support for network streaming

Power and Battery Life

• Continuous playback: up to 10 hours
• Full recharge: approximately 4 hours
• Fast charging: Qualcomm QC 3.0
• Operating temperature: 0°C to +40°C
• Firmware update supported (OTA)

Physical Characteristics

• Body material: 904L stainless steel
• Dimensions (W x H x D): 8.5 x 15.0 x 1.9 cm
• Weight: approximately 615 g