Astell&Kern SP4000 Copper Limited Edition Digital Audio Player
The Pinnacle of Pure Resonance - SP4000 Copper Limited Edition
The A&ultima SP4000 Copper Limited Edition goes beyond a high-end portable audio player. It represents the culmination of Astell&Kern’s expertise in material engineering, precision manufacturing, and refined analog sound design.
SP4000 Copper is the brand’s most definitive answer to a single question: how far can we go in the pursuit of the ultimate sound? Copper is theoretically one of the most ideal materials for audio, yet among the most difficult to use in real products. Its exceptional electrical conductivity and superior electromagnetic shielding minimize even the finest signal loss, but its rapid oxidation and low surface stability make practical application extremely challenging.
In portable devices, which are constantly exposed to temperature changes and external environments, copper becomes an even greater risk. Rather than avoiding this challenge, Astell&Kern confronted it directly, applying an advanced multi-layer coating process that requires high technical expertise to ensure the long-term stability of 99.98% pure copper.
The exterior, too, is never design for design’s sake. High-purity copper is highly susceptible to minute deformation during machining, yet Astell&Kern’s accumulated expertise enables precise control down to the finest tolerances. Through this process, the SP4000 Copper is realized not as a mass-produced device, but as a beautifully finished high-end audio object.
Most importantly, the sound is the culmination of this relentless craftsmanship. Free from exaggeration or coloration, it delivers the texture and weight of instruments, the pace and breath of performance, rendered as an exceptionally refined expression of the original sound—enhanced by the inherent characteristics of copper.
Deep, authoritative bass, a dense and articulate midrange, and treble that fades naturally come together as a single, cohesive flow, allowing emotion to be fully revealed through sound. Beyond simply “great sound," it offers an experience where the true value of the original recording is faithfully realized.
The SP4000 Copper Limited Edition embodies Astell&Kern’s unwavering commitment to surpassing limits without compromise. Created for those who truly understand the essence of pure sound, SP4000 Copper sets a new standard for what high-end audio can be.
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 distills 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.
Enhanced Signal Processing Capabilities with 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 131dB, on par with the independent dual audio circuit of its predecessor.
Supports High Driving Mode for Premium Sound Performance
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.
Minimized Group Delay with Proprietary ESA (Enhanced Signal Alignment) Technology
The SP4000 features proprietary ESA (Enhanced Signal Alignment) technology, which significantly improves one of audio’s long-standing challenges—group delay. ESA technology aligns frequency signals to arrive more uniformly, minimizing frequency distortion and dramatically enhancing so