By: Dipin Sehdev
At High End Munich 2025, Astell&Kern lifted the veil on its long-rumored flagship digital audio player (DAP), the A&ultima SP4000—a hyper-engineered, luxuriously overbuilt successor to the highly acclaimed SP3000. While the global market for high-end DAPs may remain niche, Astell&Kern continues to lean into that niche with unapologetic commitment. And with the SP4000, it may have created the ultimate portable player for those who refuse to compromise on sound—price be damned.
From its next-gen DAC architecture to full Android OS integration, the SP4000 is less a gadget and more a statement piece for audiophiles who want it all—and want it lossless.
Built to Obsess: New Octa Audio Circuit Architecture
At the heart of the SP4000 lies a dramatically overhauled Octa Audio Circuit Architecture, representing a significant leap beyond the 1:2 DAC configuration of the SP3000. Astell&Kern now pairs four AK4191 digital signal processors with four AK4499EX DACs, creating a symmetrical 1:1 digital-to-analog signal path.
Each channel receives its own dedicated signal chain, reducing noise and increasing precision. The result is a true quad-DAC configuration, long considered impractical in a portable chassis until now. This design separates digital and analog processing into distinct hardware blocks, eliminating crosstalk and keeping the analog signal path whisper-quiet—exactly the kind of thing purists obsess over.
Dual Op-Amps and High Driving Mode
For those driving high-impedance headphones, the SP4000 introduces dual OPAMPs operating in parallel, significantly enhancing power output and headroom without compromising the noise floor. This setup supports the new High Driving Mode, an advanced amplification setting designed to widen the soundstage and improve transients while maintaining signal integrity.
Astell&Kern also introduces Enhanced Signal Alignment (ESA) technology to minimize group delay—the phenomenon where different frequencies arrive at the listener's ear out of sync. ESA ensures time alignment across all frequencies, delivering a more coherent, life-like presentation.
Going Full Android—Finally
Perhaps the most overdue evolution: the SP4000 finally runs full Android OS with Google Play Store support, ending years of frustration over sideloaded apps and limited compatibility. No more manually installing APKs just to access streaming apps like Qobuz, TIDAL, or Apple Music. Everything is native now—just download, install, and play.
Astell&Kern ensures that full Android doesn’t mean sacrificing audio quality. Their A&K Direct Path (ADP) bypasses Android’s standard audio stack to allow bit-perfect, lossless output, preserving the purity of hi-res audio streams.
DAR and VSE: Upsampling, Reimagined
The SP4000 marks the debut of Astell&Kern’s second-generation DAR (Digital Audio Remaster) engine, now paired with VSE (Virtual Sound Extension) technology. VSE first reconstructs high-frequency harmonic content often lost in compressed or digitally processed tracks, then DAR upsamples the signal with increased finesse and nuance.
This dual-stage approach isn't just about increasing sample rates—it’s about restoring musicality and spatial dimension, bridging the gap between digital reproduction and analog intimacy.
Military-Grade Build and Engineering
Housed in 904L stainless steel, the SP4000 is sculpted from the same material used in high-end mechanical watches. It’s an aesthetic and functional choice: corrosion-resistant, hypoallergenic, and gorgeous. The DAP is available in Black or Silver, and ships with a shrunken calfskin leather case from Germany’s Perlinger tannery—an accessory that wouldn’t feel out of place in a high-fashion boutique.
Inside, Astell&Kern uses Any Layer HDI PCB technology, typically reserved for premium smartphones or defense-grade electronics. This dense, multi-layered board layout enables a clean, compact layout without compromising signal integrity.
A new 99.9% pure copper shield can reduces electromagnetic interference to near-zero levels—preventing digital noise from bleeding into the analog signal path.
Crimson Theme and UI 4.5
Aesthetically, the SP4000 introduces Astell&Kern UI 4.5, a refresh of its dark-themed “Crimson” interface. Beyond its sleek animations and rotating LP visualizer, it offers smoother navigation, faster response, and a more modern look that still respects A&K’s signature style.
Massive Screen, Massive Storage
The SP4000 features a 6-inch 2160×1080 full HD touchscreen, a significant leap from the SP3000’s 5.46-inch panel. Colors are rich, details are sharp, and UI elements finally have room to breathe.
Storage also gets a bump: 256GB internal memory, plus microSD expansion up to 1.5TB. That’s enough space for tens of thousands of hi-res FLACs or DSD albums—because carrying your entire library isn’t optional anymore.
Bluetooth, Streaming, and Roon Readiness
The SP4000 supports aptX Adaptive and LDAC, finally bringing true 24-bit Bluetooth streaming to an Astell&Kern flagship. It also functions as a Bluetooth DAC with BT Sink mode, meaning your phone can stream directly into it while the SP4000 handles all decoding and amplification.
File transfer is handled via AK File Drop, and USB DAC functionality is available for both Windows and macOS. Roon Ready certification is expected later in 2025.
Format Support and Crossfeed
As expected, the SP4000 plays virtually every file type imaginable: DSD up to 512, PCM up to 32-bit/768kHz, and all common formats including WAV, FLAC, ALAC, AIFF, and MQA.
A new Crossfeed mode simulates speaker-style listening by subtly blending left and right channels—ideal for long sessions with over-ear headphones.
Specs At a Glance
| Feature | A&ultima SP4000 |
|---|---|
| DAC Chipset | 4x AK4499EX with 4x AK4191 |
| Op-Amp | Dual OPAMPs in parallel |
| CPU | Octa-Core |
| OS | Android with Google Play |
| Display | 6.0″ IPS LCD, 2160×1080 Full HD |
| Storage | 256GB internal + microSD (up to 1.5TB) |
| Wi-Fi | Dual-band Wi-Fi (2.4GHz/5GHz) |
| Bluetooth | LDAC, aptX Adaptive, BT Sink |
| Audio Formats | DSD512, PCM 32bit/768kHz, MQA, FLAC, etc. |
| USB | USB-C with Quick Charge 3.0 |
| Output Ports | 3.5mm unbalanced, 2.5mm/4.4mm balanced |
| Playback Time | ~10 hours (varies by mode and codec) |
| Weight | ~480g |
| Material | 904L Stainless Steel |
| Case | Shrunken calf leather from Perlinger |
| Price | TBD (~$4,499 estimated) |
| Availability | Q3 2025 (Global) |
SP4000 vs SP3000 vs SP3000M: A True Flagship Leap
| Category | SP4000 | SP3000 | SP3000M |
|---|---|---|---|
| OS | Full Android + Google Play | Locked Android (no Play) | Locked Android |
| UI | AK UI 4.5 | AK UI 4 | AK UI 4 |
| DAC Architecture | 1:1 (4x4 AKM pairing) | 1:2 (2 DSPs/4 DACs) | 1:2 |
| Op-Amp Configuration | Dual Parallel | Single | Single |
| Screen | 6″ 2K | 5.46″ Full HD | 4.1″ HD |
| Bluetooth | LDAC, aptX Adaptive | LDAC, aptX HD | LDAC, aptX HD |
| DAR Tech | 2nd Gen + VSE | 1st Gen DAR | 1st Gen DAR |
| ESA Support | Yes | No | No |
| Audio Shielding | 99.9% Pure Copper | Partial Shielding | Partial Shielding |
| Price (Launch) | ~$4,499 (est.) | $3,699 | $2,399 |
Availability and Pricing
The Astell&Kern A&ultima SP4000 will be available globally in Q3 2025, distributed through authorized A&K dealers, online retailers, and select luxury audio stores. Pricing has not been officially confirmed, but industry insiders suggest a launch price in the range of $4,499 USD.
For context, the SP3000 launched at $3,699 and still commands near that price on the secondhand market. Expect the SP4000 to follow suit—and possibly push past that if initial demand outstrips supply.
Final Verdict: A Player for the Unapologetic Purist
The Astell&Kern A&ultima SP4000 is more than a DAP—it’s a mobile statement of sonic intent. With an obsessive engineering ethos, uncompromising DAC layout, and finally a full Android ecosystem, it sets a new bar for flagship audio players.
Yes, it’s overkill for most. And yes, it costs more than a used Honda Civic. But for those chasing the absolute edge of portable audio—with the ears and equipment to justify it—the SP4000 is the new benchmark.
If you're asking whether it's "worth it," you're asking the wrong question. For the audiophile elite, the SP4000 isn’t a luxury—it’s a necessity.
We look forward to the reviews and CE Critic Score.
