Astell&Kern, global player in portable high-resolution audio players and accessories, has announced an expansion of the A&ultima flagship player line with the launch of the SP4000T and Clarus in-ear monitor, both making their global debut at the High End Show, June 4–7 at the Austria Center Vienna.
Astell&Kern continues to push the boundaries of portable high-resolution audio with two new flagship introductions that combine retro-inspired analogue design with cutting-edge digital engineering. The SP4000T digital audio player and Clarus in-ear monitor represent the brand’s latest step in merging heritage sound technologies with modern performance demands.
The SP4000T is the industry’s first digital audio player to feature RAYTHEON JAN6418 MIL-Spec vintage vacuum tubes in a quad configuration. Designed with independent dual-tube structures dedicated to left and right channels, the architecture brings channel separation previously associated with high-end home tube amplifiers into a portable device. Each tube is individually measured for noise and gain characteristics before pairing and is isolated through modular flexible PCBs and a multi-layer structure designed to minimise vibration and electrical interference.
Triple Tube Mode introduces up to 54 possible sound combinations by combining Triode, Ultra Linear and Pentode modes. Triode Mode delivers rich harmonic warmth and emotional depth, Ultra Linear balances tonal richness with control and precision and Pentode Mode provides maximum output, energy and dynamic impact. These are further enhanced through Astell&Kern’s T Series Signature Triple AMP Mode and tube current adjustments, creating what the company describes as a true analogue sound palette.
Additional flexibility is provided through OP AMP Mode for precision and dynamics, Tube AMP Mode for analogue character and a five-stage hybrid amplification system that blends both approaches. A second-generation five-stage anti-microphonic architecture reduces vibration-induced noise in the vacuum tubes, supporting stable performance in portable environments.
At its core, the SP4000T integrates Astell&Kern’s TERATON ALPHA technology alongside dual flagship AK4499EX DACs and AK4191EQ processors in a fully discrete, channel-separated design. High Driving Mode, Enhanced Signal Alignment technology and Advanced DAR upsampling work together to improve clarity, harmonic integrity and spatial accuracy.
On the digital side, the SP4000T runs Android 15 with full Google Play Store support while maintaining bit-perfect playback via Astell&Kern Direct Path technology, which bypasses Android sample rate conversion. A dual Wi-Fi antenna system enhances connectivity, delivering up to twice the 5GHz download speed of previous models in internal testing.
Additional engineering refinements include Any Layer HDI PCB technology and a 99.9% pure copper shield can to reduce noise and electromagnetic interference. Storage includes 256GB internal memory with microSD expansion up to 1.5TB, supporting up to 32-bit/768kHz PCM and DSD512 playback.
Connectivity includes dual-band Wi-Fi, DLNA, USB DAC support for Mac and Windows, Bluetooth with aptX Adaptive and LDAC, BT Sink mode, ReplayGain, AK File Drop and USB PD 3.0 fast charging. A 6-inch Full HD display is complemented by crossfeed controls for a more speaker-like headphone presentation and reduced listening fatigue.
The SP4000T is supplied with premium leather case options including Cognac-coloured Minerva leather from Badalassi Carlo, a black soft cowhide option from Gruppo Mastrotto and an olive vegetable-tanned leather variant. Each features an integrated stand mechanism for added usability.
Alongside the player, Astell&Kern introduces Clarus, a nine-driver tribrid in-ear monitor constructed from 6061-T6 aluminium. Each driver is dedicated to a specific frequency range, combining a dynamic driver for low frequencies, balanced armature drivers for mids and highs and MEMS drivers for ultra-high frequency reproduction. The result is a design focused on clarity, precision and faithful sound reproduction across the entire spectrum.
Clarus will be available for demonstration at the Astell&Kern booth at High End Vienna 2026. Pricing and availability will be confirmed in due course.
