Astell&Kern SP4000 copper

The SP4000 from Astell&Kern is a high-end audiophile music player. The result of three years of development after the SP3000, it introduces a brand-new Quad DAC architecture to the lineup, full Android OS integration, and carefully selected materials. Its chassis is made of stainless steel, and its ceramic back benefits from a PVD treatment. This model implements several proprietary technologies and is aimed at users looking for a portable device with extensive audio performance and meticulous build quality.

Revolutionary audio architecture

At the heart of the SP4000 is an Octa audio circuit architecture with a true Quad DAC, marking a major technical break. 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 to shared architectures and makes it possible to achieve an exceptional signal-to-noise ratio of 131dB.

The parallel configuration of the operational amplifiers is another notable innovation. High Driving mode uses 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 exceptional 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.

The first audiophile Android OS

The SP4000 marks Astell&Kern’s entry into the era of modern streaming with full Android OS integration. This revolution provides access to the Google Play Store and installation of third-party applications such as Tidal, Qobuz, Spotify, or Apple Music. 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 while browsing music collections, preserving 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 introduces the use of 904L stainless steel in portable audio, a material previously reserved for luxury watchmaking. This premium construction is complemented by a ceramic back treated with PVD (Physical Vapor Deposition), offering exceptional scratch resistance and refined aesthetics.

The whole is protected by a Perlinger leather case, crafted by German artisans renowned for their cold-tanning techniques. This process preserves the leather’s natural patterns while allowing deep coloration 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 likely to affect the audio circuits, a first in the Astell&Kern range.

Proprietary technologies

ESA (Enhanced Signal Alignment) technology tackles the persistent challenge of group delay in digital audio. This phenomenon, in which different frequencies pass through circuits at varying speeds, 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 an advanced upsampling process, this technology makes it possible to recover harmonics often lost during digital processing, thus offering unmatched finesse of execution. This process restores lost harmonics and uses more powerful oversampling to bring refinement and naturalness to the 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 with previous models.

Modern connectivity and versatility

The SP4000 integrates extended connectivity capabilities 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, which allows 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 computer, meeting the needs of high-end audio setups.

Roon Ready certification is in the finalization stage 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 goes well beyond 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 makes it possible to build and carry a considerable 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 major 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 everyday use, while materials move up 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 turns the SP4000 into a reference wireless DAC, allowing you to instantly improve the audio quality of external sources such as a computer. For high-end audio setups, this avoids the purchase of a dedicated DAC while preserving Astell&Kern’s sound signature.

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 applications.

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

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

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 through 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 the Google Play Store and compatibility with third-party audio applications

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 support (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