• First Full-Android Flagship with Google Play – SP4000 is the first Astell&Kern player running full Android, enabling direct access to apps like Spotify, TIDAL, and Qobuz—no sideloading required—while preserving bit-perfect playback via AK’s proprietary ADP (Astell&Kern Direct Path) audio engine
• True Quad‑DAC Octa-Circuit Architecture – Uses a 1:1 pairing of four AK4191 digital processors with four AK4499EX DACs (a real Quad-DAC implementation). This architecture dramatically improves signal separation and delivers an exceptional 131 dB SNR
• High Driving Mode with Parallel Op-Amps – Featuring twice the number of op-amps in a parallel configuration, it drives demanding headphones and IEMs with power and dynamics—adding punch without increasing noise—much like engaging a four-wheel-drive mode
• ESA – Enhanced Signal Alignment– Proprietary ESA tech aligns frequency bands to arrive in perfect sync, dramatically reducing group delay and improving clarity, coherence, and imaging
• Ultra-Low Noise LDO Regulator – Incorporates a high-performance LDO power regulator—borrowed from medical/5G tech—that cuts power supply noise by up to 97%, delivering ultra-clean, interference-free playback
• Precision Any-Layer HDI PCB & 99.9% Copper Shielding – Utilises smartphone-grade HDI PCB to minimise signal loss, and encloses the audio circuit in a 99.9% pure copper shield can to block EMI/RF noise—offering pristine analogue purity
• Advanced DAR v2 + VSE Restoration – The upgraded DAR (Digital Audio Remaster) system uses a two-stage process: first Virtual Sound Extender (VSE) restores lost harmonics; then DAR up-samples. The result is richer, more immersive, architecturally accurate sound

The Limited Edition A&ultima SP4000 Copper showcases Astell&Kern’s ultimate material and sonic mastery. Crafted from 99.98% pure copper, it delivers uncolored, lifelike sound with deep bass, rich mids, and naturally refined highs—created for those who demand the truth of the original recording.

Features

• Octa audio circuit for enhanced signal processing
• High Driving Mode for premium sound output
• ESA technology minimises group delay
• Ultra-low-noise LDO regulator for superior noise control
• Any Layer Type PCB for precise signal integrity
• 99.9% pure copper shield can for maximum isolation
• Full Android OS support - a first for 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 line-up 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.

Octa Audio Circuit Architecture

In the SP3000, the digital-to-analogue 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.

High-End Shrunken Calfskin Case

The SP4000 is packaged with a premium leather case crafted from Shrunken Calf by Perlinger, Germany’s world-renowned leather house. Founded in 1864 and spanning five generations of craftsmanship, Perlinger supplies the finest leather to luxury brands across the globe—blending time-honoured tradition with modern techniques.

The Shrunken Calf leather used in the case is made from the soft, delicate hide of calves under one year old. It is processed using a chrome tanning method to preserve its natural texture, then uniquely shrunk using special agents—not heat—to retain its organic grain and wrinkles.

Following an aniline dyeing process, Perlinger’s proprietary pigments are added to achieve a deep, vibrant color. Their advanced anti-aging treatment ensures that this richness lasts over time, complementing the SP4000 with a leather case that embodies lasting beauty, durability, and luxury.