Astell&Kern SP4000

The Astell&Kern SP4000 is the A&ultima flagship digital audio player, a three-year evolution beyond the SP3000, built around a true Quad DAC implementation using four AK4191EQ digital processors each paired one-to-one with a single AK4499EX DAC. A 904L stainless steel chassis, full Android OS with Astell&Kern's proprietary ADP bit-perfect streaming path, and a 6-inch 2K display make it the most technically ambitious portable music player Astell&Kern has produced.

Type and Technology

Flagship digital audio player. True Quad DAC architecture: four AK4191EQ digital modulators each directly paired with one AK4499EX DAC in a 1:1 signal ratio, eliminating noise distribution between DACs and achieving 131dB balanced SNR. Octa-core Snapdragon 6125 processor with 8GB DDR4 RAM. ESA (Enhanced Signal Alignment) technology minimizes group delay for improved sound clarity. Ultra Low Noise LDO Regulator reduces power supply noise by up to 97%. Any Layer HDI PCB for precision circuit layout in a compact space. 99.9% pure copper Shield Can for electromagnetic interference blocking. Full Android OS with Astell&Kern Direct Path (ADP) for bit-perfect lossless playback from streaming services. Advanced DAR technology: dual-stage upsampling via VSE harmonic recovery then DAR engine. Six selectable DAC filter modes. Octa-core CPU. Supports PCM up to 32-bit/768kHz and DSD512. Outputs: 3.5mm unbalanced, 4.4mm balanced, optical 3.5mm. Wi-Fi 802.11 a/b/g/n/ac (2.4/5GHz). Bluetooth 5.0 with aptX HD, LDAC, LHDC, SBC, AAC. 256GB internal storage plus microSD slot (up to 1.5TB). 6,780mAh battery, approximately 10 hours playback. 6-inch 2180x1080 2K touch display.

Sound Character

The SP4000's Quad DAC architecture achieves the same 131dB balanced SNR as the SP3000's independent dual audio circuit despite having four DAC chips rather than two, by solving the noise challenges of quad implementation through the 1:1 AK4191/AK4499 pairing. The result is a presentation of exceptional channel separation, dynamic range, and low-level resolution, with the ESA group delay correction adding a further layer of transient clarity and coherence across frequencies.

Build and Finish

904L stainless steel body, a grade of stainless used in luxury watches for its exceptional hardness, corrosion resistance, and surface quality, machined by Astell&Kern's artisans. Available in Black and Silver. Includes premium Shrunken Calf leather case by Perlinger, Germany's renowned luxury leather house established in 1864. 6-inch 2K display. Physical volume wheel. QC 3.0 fast charging (approximately 5 hours to full). 615g.

Best For

Audiophiles who want the absolute ceiling of portable digital audio performance in a luxury-finished chassis with full streaming app support and bit-perfect Android OS integration.

What's in the Box

• Astell&Kern SP4000 digital audio player
• Shrunken Calf leather case by Perlinger
• USB-C cable
• Documentation

Specifications