Astell&Kern SP4000 black

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

Revolutionary audio architecture

At the heart of the SP4000 is 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 in which 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 131dB signal-to-noise ratio.

The parallel configuration of the operational amplifiers is another major innovation. 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 finest details while maintaining exceptional dynamics, creating a denser, 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 era of modern streaming with full Android OS integration. This breakthrough provides access to the Google Play Store and the installation of third-party applications such as Tidal, Qobuz, Spotify, and 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 when browsing music collections, while retaining 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 the CPU, memory, and wireless communication components into a single module, optimizing energy efficiency.

Exceptional materials and construction

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

The unit is protected by a Perlinger leather case, crafted by German artisans renowned for their cold-tanning techniques. This process preserves the natural patterns of the leather 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 that could affect the audio circuits, a first in the Astell&Kern range.

Proprietary technologies

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

The SP4000 introduces the next-generation Advanced DAR (Digital Audio Remaster). Thanks to an advanced upsampling process, this technology recovers harmonics often lost during digital processing, delivering unparalleled refinement. 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 advancement 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 features extensive connectivity capabilities with dual-band Wi-Fi and DLNA compatibility for network streaming. Bluetooth 5.0 supports the 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 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 256GB 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 provides 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.

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 noise 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 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