A Portable Hi-Fi Great Just Dropped a Grail-Worthy Music Player

It claims to combine the best of both analog and digital audio technologies.

Close-up of a metallic device corner with a textured silver knob, a small port, and a red-lit screen edge.

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By Tucker Bowe

Published May 29, 2026

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Updated May 29, 2026

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Last May, Astell&Kern introduced a new flagship portable hi-fi player, A&ultima SP4000, for the first time in three years. It costs $4,290.

Then, earlier this year, the Korean audio maker introduced a “Copper Edition” version of that same flagship. Because of the material’s natural acoustic properties, it promised a more nuanced sound. This model, the A&ultima SP4000 (Copper Edition), costs $4,499.

Now, the brand has introduced what appears to be another iteration of its flagship player in the A&ultima SP4000T. Only this model has several key upgrades and aims to deliver a warmer, more analog-like sound.

Astell&Kern A&ultima SP4000T

Silver digital music player with a purple-lit volume knob and black wired in-ear monitors on dark green leather upholstery. — The SP4000T is the next evolution of the company’s flagship portable hi-fi player.

A portable hi-fi “first”

The SP4000T is the newest addition to Astell&Kern’s flagship A&ultima range of portable hi-fi players. And, as the “T” indicates, its main upgrade is that it’s been integrated with four vacuum tubes.

Specifically, the SP4000T features Raytheon JAN6418 MIL-Spec vintage vacuum tubes in a quad configuration. It’s the first portable hi-fi player to have such, according to the brand. This enables it to deliver a warmer sound profile, which vacuum tubes are known for.

Two sleek, angular digital audio players with black and gold finishes displayed on a glowing platform surrounded by vintage vacuum tubes. — The SP4000T is the first digital audio player to feature Raytheon JAN6418 MIL-Spec vintage vacuum tubes in a quad configuration.

Black geometric audio amplifier with red illuminated display surrounded by glowing vacuum tubes on a glass shelf. — The SP4000T features a fully discrete circuit architecture that separates digital and analog signal processing, with dual flagship AK4499EX DACs and dedicated AK4191EQ processors per channel.

But it goes beyond just the vacuum tubes. Astell&Kern is marketing the Astell&Kern as “retro meets modern,” meaning that it combines the best of both digital and analog technologies. And that’s best exemplified by the SP4000T’s all-new Triple Tube Mode.

This mode gives listeners an immense amount of control over SP4000T’s sound profile. They can choose from up to 54 combinations of tube and amp current configurations, so the sound is exactly what they want (and can change based on the music genre they’re listening to).

Silver digital music player with a red volume knob connected to black in-ear monitors with braided cables on a black leather surface. — The SP4000T supports native playback up to 32-bit/768kHz PCM and DSD51.

Close-up of a metallic device with a faceted edge and a textured silver crown with red accents on a dark background. — According to the brand, the A&ultima SP4000T “combines the best of cutting-edge digital audio with classic analogue technology.”

Tube warmth, custom sound

For listeners who don’t need that much control, Astell&Kern has given the SP4000T three distinct tube sound modes (Triode, Ultra Linear and Pentode), each delivering its own unique sonic character.

There’s also a hybrid mode that blends the strengths of both tube and op-amp amps. Astell&Kern claims this allows “listeners to fine-tune the balance between analog warmth and high-resolution transparency to match their personal listening preferences.”

Copper and black Astell&Kern portable music player with attached silver braided cable and black earphones on a dark surface. — Thanks to a transparent back window, you can see the glow of the vacuum tubes within.

Metallic digital audio player with earphones and vacuum tube on a leather desk mat next to a closed laptop and pen stand. — Thanks to a new Triple Tube Mode, listeners can choose from up to 54 combinations of tube and amp current configurations.

Like its predecessors, the SP4000T runs Android with full Google Play Store support, giving you access to all the popular streaming apps. And it’s integrated with the brand’s proprietary ADP (Astell&Kern Direct Path) technology, which “bypasses Android’s standard sample rate conversion limitations” and enables “true lossless, bit-perfect playback from streaming services.”

One other upgrade Astell&Kern has equipped the SP4000T with is a dual Wi-Fi antenna design (a first for the brand), which promises to help deliver significantly faster and more stable download speeds.

Two Astell&Kern portable music players, one black with copper cable and one silver with screen displaying "Difference In Sound Quality," on a desk. — The A&ultima SP4000T will come in two models: copper or stainless steel. Expect the former to be more expensive.

Availability and pricing

Astell&Kern will offer the SP4000T in two different models: stainless steel and copper. As for price and availability, the company has yet to reveal the information (although it claims that it’ll be announced “shortly”).

We’re guessing the SP4000T will cost north of $4,290, which is what the current flagship costs. And the copper model will be even more expensive.

Two sleek digital music players with angular designs, one black and one gold, displayed on clear stands surrounded by glowing vacuum tubes.

Astell&Kern SP4000T

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About the Author: Tucker Bowe has been on Gear Patrol’s editorial team since 2014. With a passion for consumer tech and hi-fi, he tracks everything from headphones and turntables to smartphones and wearables. If it lights up or makes noise, he probably covers it.

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