Astell&Kern ULTIMA SP4000

Astell&Kern A&ultima SP4000 - The New Benchmark for High-End Portable Audio

With the A&ultima SP4000, Astell&Kern presents its most advanced digital audio player to date. Developed three years after the groundbreaking SP3000, this new flagship redefines the possibilities of portable high-resolution playback. The SP4000 combines exceptional sound quality with state-of-the-art audio technology and luxurious craftsmanship – designed for music lovers who demand uncompromising quality, even on the go.

From the completely redesigned signal architecture to the elegant housing design, every detail has been engineered to exceed the expectations of the most discerning audiophiles.

Octa Audio Architecture – Advanced Signal Processing

At the heart of the SP4000 is a new signal architecture: Octa Audio Architecture. It combines AK4191 Digital Processors with AK4499EX DACs in a consistent 1:1 configuration, creating a true quad-DAC structure.

This architecture avoids the usual splitting of digital signals, which often causes additional interference. Instead, digital and analog signal processing work strictly separately:

• AK4191EQ handles digital signal modulation
• AK4499EX ensures precise analog conversion

The result is a particularly clean, detailed, and spatial sound reproduction with exceptional clarity.

High Driving Mode – Power and Control

The High Driving Mode uses a parallel OPAMP structure to increase output power without raising the noise floor.

This results in:

• greater dynamic range
• improved detail resolution
• powerful and stable output

Even demanding headphones can be driven effortlessly, while fine nuances and musical dynamics are fully preserved.

ESA Technology – Precise Signal Alignment

With ESA (Enhanced Signal Alignment), Astell&Kern addresses a known problem in digital signal processing: the so-called Group Delay.

ESA ensures that frequency components from different ranges arrive at the output precisely synchronous in time. This improves:

• timing and rhythmic precision
• stereo imaging
• transparency and clarity

The music appears more immediate, natural, and spatially stable.

Ultra-Low-Noise LDO Regulator

A newly developed Low-Dropout Regulator (LDO) reduces power supply interference by up to 97% compared to previous models.

This technology, originally from high-precision applications such as medical technology or 5G communication, ensures in the SP4000:

• a particularly stable voltage supply
• minimized electrical noise
• exceptionally pure sound reproduction

DAR & VSE – Digital Refinement of Music

The SP4000 features the second generation of Astell&Kern's DAR (Digital Audio Remaster) technology.

The process takes place in two steps:

1. Virtual Sound Extender (VSE) reconstructs lost harmonic information and natural sound textures.
2. The DAR-Engine then performs high-precision upsampling.

This combination ensures organic, musical reproduction with increased detail and emotional expressiveness.

Android with Bit-Perfect Streaming

For the first time, an Astell&Kern player supports the Google Play Store, allowing streaming apps to be installed directly.

To ensure Android does not compromise audio quality, the SP4000 uses Astell&Kern Direct Path (ADP) technology. This bypasses the typical Android sample rate conversion and enables bit-perfect playback – even when streaming.

High-Quality Construction Down to the Last Detail

The SP4000 also sets new standards in terms of construction.

Any Layer HDI PCB A high-density printed circuit board structure allows for a compact design with minimal signal loss.

99.9% Copper Shielding Massive copper shielding effectively protects sensitive audio circuits from electromagnetic interference.

6-inch Full-HD Display The large display with 2160 × 1080 pixels provides a brilliant display of the user interface and simultaneously improves energy efficiency.

New User Interface – 4.5 Generation UI

The revised user interface combines a modern look with particularly intuitive operation.

An LP-inspired album browser visually centers the music collection, while the Crimson Theme provides an elegant and calm display. The design philosophy is based on three principles:

• Edge – clear structure
• Simple – intuitive navigation
• Sensibility – pleasant visual representation

This reduces eye strain and simultaneously strengthens the emotional connection to the music.

Premium Leather Case from Perlinger

Included in the delivery is an exclusive leather case made from Shrunken Calf leather by the traditional German tannery Perlinger, founded in 1864.

The leather is processed using a special chrome tanning and shrinking process, which preserves the natural grain. High-quality aniline dyes and proprietary pigments provide:

• exceptional durability
• intense color depth
• luxurious feel

The result is a case that perfectly matches the high-quality appearance of the SP4000.

Technical Highlights

• 256 GB internal memory + microSD up to 1.5 TB
• 6" Full-HD Touchscreen (2160 × 1080)
• PCM up to 32 Bit / 768 kHz
• Native DSD512 Support
• Bluetooth with aptX Adaptive and LDAC
• Wi-Fi Dual Band (2.4 / 5 GHz)
• USB-DAC Function
• DLNA and USB Audio Output
• AK File Drop for wireless file transfer
• BT Sink Mode – use as a Bluetooth DAC
• Crossfeed function for optimized headphone playback
• ReplayGain for automatic volume adjustment
• approx. 10 hours battery life
• Qualcomm Quick Charge 3.0 fast charging (approx. 4 hours)

The A&ultima SP4000 is far more than a portable music player. It is an uncompromisingly developed high-end instrument for discerning music listening – a combination of state-of-the-art audio technology, luxurious design, and uncompromising sound quality. Whether streaming, listening to high-resolution music files, or critical listening: the SP4000 sets a new benchmark in the field of portable high-end audio.