After making a lasting impression with the SP3000T, Astell&Kern is taking things to the next level with the launch of the SP4000T. This new high-end DAP builds on the same formula with an all-new four-tube architecture featuring Raytheon JAN6418 tubes, enhanced with numerous settings that allow users to adjust the sound reproduction with unprecedented precision. More powerful, more versatile, and equipped with Android 15 for streaming, it stands out as one of the most ambitious portable digital audio players ever designed.
The SP4000T: a new benchmark from Astell&Kern
Unveiled a few months earlier, the SP4000 already marked a major evolution in the A&ultima range. As the successor to the highly acclaimed SP3000, it retained its dual AKM DAC conversion architecture while thoroughly modernizing its hardware platform. A new 6-inch 2K display, a more powerful processor, Android 15, Wi-Fi 6, increased amplification power, and proprietary technologies such as ESA and Advanced DAR ushered the brand’s flagship model into a new generation. With the SP4000T, Astell&Kern builds upon this technological foundation while adding an extra dimension with amplification that can now operate in tube, transistor, or hybrid modes.
A unique four-tube architecture
Launched in 2024, the SP3000T had already made a splash by incorporating two Raytheon JAN6418 miniature tubes into a DAP. Its triple amplification system, allowing users to switch between transistor, tube, or hybrid modes, quickly established it as a benchmark for portable audio. The new SP4000T builds on this philosophy while taking it to the next level in virtually every respect. The two tubes have now been replaced by a Quad Tube architecture consisting of four carefully matched Raytheon JAN6418 tubes. This configuration improves channel symmetry, increases harmonic richness, and delivers an even broader soundstage.
To preserve its musical qualities, Astell&Kern has developed a highly sophisticated anti-microphonic architecture. The tubes are mounted on independent printed circuit boards, isolated by several layers of silicone, suspended in a specialized damping system, and then protected by copper shielding. This design effectively limits vibrations and electrical interference, allowing the tubes to fully express their musicality, even when used on the go. This promises a more natural sound reproduction, exceptionally lifelike vocals, and a soundstage of remarkable depth.
Three distinct sound signatures
One of the major new features of the SP4000T is the introduction of a Triple Tube Mode. Beyond simply choosing between tube or transistor amplification, the DAP now allows you to directly adjust the tubes’ operation across three distinct configurations. Triode Mode prioritizes smoothness, warmth, and harmonic richness. Ultra-Linear Mode seeks a more neutral balance between precision and density, while Pentode Mode emphasizes the dynamics, speed, and energy of the sound reproduction. Astell&Kern has also added a Tube Current setting, which adjusts the operating voltage of the tubes across three intensity levels. This allows users to fine-tune the sound density to suit their headphones or musical preferences.
Even more powerful amplification
Astell&Kern has also redesigned the amplifier’s power supply to deliver up to 8 Vrms on its 4.4 mm balanced output, compared to 6.3 Vrms on the SP4000T. This power reserve allows it to drive even the most demanding headphones with ease while maintaining a very low level of background noise. The 3.5 mm unbalanced mini-jack output, meanwhile, delivers 4.2 Vrms of power, which is sufficient for most headphones and earbuds.
A completely modernized platform
Like the SP4000, this T version also features the brand’s latest hardware upgrades. It includes a superb 6-inch 2K touchscreen, a faster octa-core processor, Android 15, Wi-Fi 6, LDAC-compatible Bluetooth 5.2, LHDC, and aptX HD, as well as 256 GB of internal storage expandable via microSD card up to 1.5 TB. Digital-to-analog conversion continues to rely on the combination of the AK4191EQ and AK4499EX chips, with physical separation of the digital and analog processing stages to minimize interference. The DAP naturally supports playback of PCM files up to 32-bit/768 kHz as well as DSD512 files.
With the SP4000T, Astell&Kern takes its approach to high-end portable audio even further by combining the performance of the recent SP4000 with a completely redesigned analog architecture. Quadruple-tube design, Triple Tube Mode, triple amplification, increased power, and a modernized hardware platform come together to create a particularly appealing package for discerning audiophiles. By incorporating the best features of the SP4000 and SP3000T while adding new customization options, the SP4000T is already shaping up to be one of the most exclusive and sophisticated DAPs available today.
