Astell& Kern was the first company that made me desperately want a product. It was the beautiful, but somehow ill-fated SP2000T. Launched after the excellent SP2000, and affected by the shortage of AKM chips, dues to the fire of 2000, Oct 20th-23rd, when the Asahi Kasei Mycrosystems factory was severely damaged, the SP2000T did ot manage to achieve the same fame as its predecessor. It sported ESS ES9068AS in QUAD-DAC configuration and Korg Nutube 6P1 and to my ears it sounded really good. Once I’ve heard it, at the Munich HighEnd show, there was no going back.
Fast forward to 2026, Astell&Kern DAPs have been a constant presence in my sources line-up, maintaining a stable 2 pieces at any time (SP2000T, S3000T, SP3000, SR35, Activo P1, all were part of my line up at various points in time. The current line up is SR35 and SP3000. They share the stables with the amazing Nipo N2.
Recently, a good friend lent me his SP4000, which shakes my conviction that the SP3000 is the best DAP for me.
The cold facts:
| Specification / Feature | A&norma SR35 | A&ultima SP3000 | A&ultima SP4000 |
| Product Series | A&norma (Compact / Standard Line) | A&ultima (Flagship Line) | A&ultima (Flagship Line) |
| DAC Architecture | Quad CS43198 • 4× Cirrus Logic CS43198 • Quad/Dual DAC switching mode | HEXA Audio Structure (1:2) • 2× AKM AK4191EQ (Modulator) • 4× AKM AK4499EX (Dual + Dual DAC) • Physical digital/analog separation | 1:1 Octa Audio Structure • 4× AKM AK4191EQ (Modulator) • 4× AKM AK4499EX (True Quad DAC) • 1:1 direct modulator-to-DAC pairing |
| CPU / System SoC | Quad-Core CPU | Qualcomm Snapdragon 6125 Octa-Core (8GB DDR4 RAM) | Qualcomm Snapdragon 6125 Octa-Core (8GB DDR4 RAM) |
| Operating System | Proprietary AK OS (Crimson UI Theme) | Proprietary AK OS (Crimson UI) on launch, later updated to full Android | Full Android OS Integration + Google Play Store with Astell&Kern Direct Path (ADP) bit-perfect streaming |
| Chassis / Body Material | Aluminum (Charcoal Gray) | Stainless Steel 904L (Silver, Black) / 99.98% Copper / 24K Gold / Platinum | Stainless Steel 904L (Silver, Black) / 99.98% Pure Copper Limited Edition |
| Display | 3.6-inch HD (720 × 1280) Touchscreen | 5.46-inch Full HD (1080 × 1920) Touchscreen | 6.0-inch 2K (2160 × 1080) Touchscreen |
| Supported Formats & Native Decoding | Up to PCM 32-bit / 384 kHz Native DSD256 (11.2 MHz) MQA full decoder | Up to PCM 32-bit / 768 kHz Native DSD512 (22.4 MHz) MQA full decoder | Up to PCM 32-bit / 768 kHz Native DSD512 (22.4 MHz) |
| Signal-to-Noise Ratio (SNR @ 1 kHz) | • Unbalanced: 127 dB • Balanced: 130 dB | • Unbalanced: 126 dB • Balanced: 130 dB | • Unbalanced: 129 dB • Balanced: 131 dB |
| THD+N (@ 1 kHz) | • Unbalanced: 0.0005% • Balanced: 0.0006% | • Unbalanced: 0.0006% • Balanced: 0.0004% | • Unbalanced: 0.0005% • Balanced: 0.0003% |
| Crosstalk (@ 1 kHz) | • Unbalanced: -133 dB • Balanced: -145 dB | • Unbalanced: -136 dB • Balanced: -145 dB | • Unbalanced: -136 dB • Balanced: -145 dB |
| Output Level | • Normal:Unbal 2.1 Vrms / Bal 4.0 Vrms • High: Unbal 3.1 Vrms / Bal 6.0 Vrms | • Unbalanced: 3.3 Vrms • Balanced: 6.3 Vrms (No Load) | Unbalanced 4.1Vrms │ Balanced 8.2Vrms (Condition No Load) |
| Audio Outputs | • 3.5mm Unbalanced • 2.5mm Balanced (4-pole) • 4.4mm Balanced (5-pole) | • 3.5mm Unbalanced / Optical Out • 2.5mm Balanced (4-pole) • 4.4mm Balanced (5-pole) | • 3.5mm Unbalanced (0.7 Ω) / Optical Out • 4.4mm Balanced (1.7 Ω, 5-pole) |
| Key Acoustic Technologies | • Dual/Quad DAC Switching • 2-Step Gain Control • ReplayGain • AK File Drop | • TERATON ALPHA • DAR (upsampling up to 384kHz / DSD256) • 6 DAC Filters • Crossfeed • ReplayGain • AK File Drop | • Advanced DAR 2.0 with VSE (Virtual Sound Extender) • ESA (Enhanced Signal Alignment – Group Delay Reduction) • Ultra-Low Noise LDO Regulator (97% noise reduction) • 99.9% Pure Copper Shield Can • Any Layer HDI PCB • 6 DAC Filters • Crossfeed & ReplayGain |
| Built-in / Expandable Storage | 64 GB NAND / microSD slot (up to 1 TB) | 256 GB NAND / microSD slot (up to 1 TB) | 256 GB NAND / microSD slot (up to 1.5 TB) |
| Wireless & Streaming | • Dual-Band Wi-Fi (2.4 / 5 GHz) • Bluetooth 5.0 (LDAC, aptX HD) • BT Sink • Roon Ready | • Dual-Band Wi-Fi (2.4 / 5 GHz) • Bluetooth 5.0 (LDAC, aptX HD) • BT Sink • Roon Ready | • Dual-Band Wi-Fi (2.4 / 5 GHz) • Bluetooth (aptX Adaptive, LDAC, BT Sink) • Full Google Play streaming apps • Roon Ready |
| Battery & Charging | • 3,150 mAh Li-Polymer • Up to ~20 hours playback (Dual DAC mode) • ~2.5 hrs charging (5V 2A) | • 5,050 mAh Li-Polymer • Up to ~10 hours playback • ~3.5 hrs charging (Qualcomm QC 3.0) | • 6,780 mAh Li-Polymer • Up to ~10 hours playback • ~5 hrs charging (Qualcomm QC 3.0) |
| Dimensions & Weight | Compact handheld form factor | • 82.4 × 139.4 × 18.3 mm • ~493 g (SS) | • 85.0 × 149.8 × 19.5 mm • 615g (SS) |
The first ting one notices about the SP4000 is the imposing physical presence. While not as thick as some of the most famous DAPs (looking at you, N30LE), this is one hefty device. It’s also big, with a wonderful, bright screen. Just like other AK models, it has sharp corners, potentially turning its use without a case into a sort of BDSM experience. Be advised! Also, because the volume wheel doubles as the power button, it moves freely, to the point of feeling a bit flimsy, a feature carried over from the SP3000. While not my favourite volume wheel, it works well and my SP3000 is carrying its age with dignity so I have no reasons to believe the one on SP4000 would be any different.
The SP3000 has a neutral sound, with one of the leanest bass presentations, dead neutral mids and with a delicate and intricate treble delivery. One of the crispest, clear trebles I’ve encountered. The sound density is not very high, giving most IEMs ample space to breathe, and creating a large stage with or without DAR activated. The image and layering are very good. It works best with densely sounding IEMs, like the Mysticraft Tet, NGaudio Erebus, etc. but it sounds underpowered with monsters like Storm or Elysian X.
SP4000 follows the same path of neutrality, but it has a denser sound and the treble is less “grating”. While the presentation is more technical, it feels like there is less air in between instruments, making DAR a must for most IEMs. Without it, the amount of information is overwhelming, making it less pleasurable for me, compared to its predecessor. The bass and lower mids carry more grunt, without necessarily sounding elevated, being a clear departure from warm DAPs like N30LE, while clearly more muscular than SP3000. One caveat here is the High Driving Mode (HDM). With IEMs like Storm, Pentara, Elysian X, SP4000 in Normal Driving Mode felt lacking in dynamics. With one tap, though, things change dramatically, as HDM brings about improved macro and micro dynamics, pumping life into even the most demanding IEMs.
I find SP4000 to sound more detailed than SP3000 in the most part of the spectrum, with more texture and a tighter packing of the sound. With most IEMs, bass control is stricter, note weight is improved over SP3000, but there is a key area where SP3000 outshines the SP4000, and that is treble. With most of my library composed of varieties of rock, from mellow to extreme death metal, jazz and some older pop, I place a lot of value onto hearing the cymbals loud and proud. Occasional splashiness does not bother me. The way SP3000 presents the treble, with a good combination of body, shimmering and crispiness, remains unmatched to my ears. At least with some IEMs, like Oriolus Traillii JP, Erebus, UMxMusicteck Pentara.
For IEMs with slightly thinner notes, SP4000 is a gift from heaven, adding just enough meat on the bone, without altering the overall tuning.
One interesting find is the Mysticraft Tet, which is one of the thickest sounding IEMs, matched maybe only by the Epic Audio Intoxication. I would have expected it to sound unbalanced on the SP4000, but it is quite the contrary. Maybe through tighter control, maybe via dark magic, SP4000 makes is shave off some weight, elevating the sound, while maintaining the mid range lushness and bringing the treble more forward spatially. A highly recommended match.
In terms of functionality, the two A&Ultimate DAPs are now identical, since the SP3000 has also been updated to full Android. Funny enough, SP3000 boots up a bit faster than SP4000, but the difference is diminutive.
Upgrading from SP3000 to SP4000 makes sense if you have hard to drive IEMs and don’t want to use an external amp or if you favour a dense(r) sound. Personally, I am going to stick to SP3000 for a bit longer…but the edge is really tiny.
