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Astell&Kern A&ultima SP4000T Digital Audio Player
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The A&ultima SP4000T is the culmination of nearly two years of dedication and exploration, beginning from the planning and development stages of SP3000T.
Using the canvas of SP4000, the essence of digital sound, Astell&Kern held onto one defining question over the past two years: “How can we bring deeper emotion through analog sound?”
- Industry-first DAP featuring JAN6418 MIL-Spec tubes in a Quad configuration
- Triple Tube Mode with Triode, Ultra Linear, and Pentode operating modes
- Triple AMP System with OP AMP, Tube AMP, and five-stage Hybrid AMP modes
- Dual AK4191EQ digital processors and dual AK4499EX flagship DACs
Ships in USA
30 Day Returns
Free 1 or 2 Day
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Our Take
The A&ultima SP4000T combines Astell&Kern’s flagship digital architecture with an unusually flexible analog amplification system. Its Quad Raytheon vacuum-tube configuration, three tube-operating modes, Triple AMP System, and adjustable tube current provide up to 54 combinations for tailoring the presentation. Listeners can move between the clarity and expansive soundstage of OP AMP mode, the rich harmonic character of Tube AMP mode, and five Hybrid AMP stages that blend analog warmth with high-resolution output. Beyond its analog capabilities, the SP4000T is also designed to integrate seamlessly into modern streaming ecosystems with support for Roon Ready and Qobuz Connect. Together, these features complement the SP4000T's advanced hardware by providing a streamlined, high-resolution listening experience for both locally stored music and network streaming.
ANALOG SOUND PALETTE
The A&ultima SP4000T is the industry’s first digital audio player to use four MIL-Spec Raytheon JAN6418 vintage vacuum tubes in a Quad configuration. Independent dual-tube structures are dedicated to the left and right channels, bringing a channel-separated architecture traditionally associated with high-end home tube amplifiers into a portable player.
The four tubes operate in a differential configuration, with each pair arranged in mirror symmetry. This configuration amplifies the music signal while mutually cancelling common-mode noise. Each tube is measured for its noise and gain characteristics before pairing and is isolated through independent modular flexible PCBs and a multilayer architecture.
Triple Tube Mode combines Triode, Ultra Linear, and Pentode operation with the Triple AMP System and three-level tube-current adjustment, providing up to 54 possible combinations. Triode mode emphasizes rich harmonic texture and lingering decay, Ultra Linear mode balances tonal color with solid output, and Pentode mode maximizes output and dynamic range for a cleaner and more forceful presentation.
“The delicacy of Triode, the balance of Ultra Linear, the dynamics of Pentode.”
TRIPLE AMP SYSTEM
Built on Astell&Kern’s Teraton Alpha technology, the SP4000T offers three distinct amplification approaches. OP AMP mode focuses on high resolution, clarity, dynamics, and an expansive soundstage, while Tube AMP mode emphasizes the warm texture and emotional depth associated with real vacuum-tube amplification.
Hybrid AMP mode combines analog character with high-resolution output through five adjustable stages, allowing listeners to select the balance of tube warmth and solid-state precision that best complements their headphones, music, and personal preferences.
ADVANCED AUDIO ARCHITECTURE
The SP4000T uses a HEXA audio circuit structure built around two AK4191EQ digital delta-sigma modulators and two AK4499EX analog DACs. Digital and analog signal processing are physically separated to reduce noise and preserve signal integrity, while High Driving Mode, Enhanced Signal Alignment, Advanced DAR, and Astell&Kern Direct Path further support detailed, bit-perfect high-resolution playback.
A five-stage second-generation anti-microphonic architecture isolates the four vacuum tubes using modular flexible PCBs, silicone cushioning, custom-fit silicone around the tube leads, suspended silicone dampers, and copper shield cans to suppress vibration-related tube noise.p>
Comfort & Build
The SP4000T features a stainless-steel and copper body built around Astell&Kern’s “Burst” design concept, which visually represents concentrated energy expanding outward from the volume wheel. Its 6-inch 2K touchscreen provides a large interface for navigation, while the included Cognac-colored case uses Minerva leather from the Italian tannery Badalassi Carlo and includes a rear cutout that reveals the vacuum-tube LED glow.
Included + Specs
What’s Included
- Astell&Kern A&ultima SP4000T Digital Audio Player
- Premium Cognac Minerva Leather Case
- 256GB of Built-In NAND Storage
- USB Type-C Charging and Data Input
Key Specs
- DAC: AK4191EQ x2 + AK4499EX x2
- Vacuum Tubes: Raytheon JAN6418 x4 (Quad Tube)
- Display: 6-inch 2K (2160 x 1080) touchscreen
- Outputs: 3.5 mm single ended unbalanced and digital optical; 4.4 mm balanced
- Output Level: 4.2 Vrms unbalanced; 8 Vrms balanced
- Output Impedance: 0.7 Ω (3.5 mm Unbalanced) │ 1.7 Ω (4.4 mm Balanced)
- Frequency Response: ±0.006 dB (20 Hz–20 kHz), ±0.06 dB (20 Hz–70 kHz)
- Signal-to-Noise Ratio (S/N): 124 dB @ 1 kHz (Unbalanced) │ 125 dB @ 1 kHz (Balanced)
- Crosstalk: -136 dB @ 1 kHz (Unbalanced) │ -145 dB @ 1 kHz (Balanced)
- Total Harmonic Distortion + Noise (THD+N): 0.0006% @ 1 kHz (Unbalanced) │ 0.0004% @ 1 kHz (Balanced)
- Storage: 256GB internal; microSD up to 1.5TB
- Wireless Connectivity: Wi-Fi 802.11 a/b/g/n/ac/ax and Bluetooth 5.2
- Battery Capacity: 7,450 mAh, 3.8 V Li-Polymer
- Playback Time: Approximately 10 hours
- Weight: Approximately 19.9 oz (565 g)
Features
Overall rating: 5.0 / 5 from 4 reviews.
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Reviews
HeadAmp delivers quality service
"Great replacement for Hugo Chord. More musicality, less sharpness. Great with low impedance headphones like Stellia. More importantly, I recommend HeadAmp service. Upgraded product, fast shipment, follow up."
Do it!
"I recently purchased the SP3000T Digital Audio Player, and it has truly exceeded my expectations. Paired with my Hifiman Arya Organic headphones, the sound quality is nothing short of phenomenal. The SP3000T delivers a rich, detailed, and immersive audio experience that brings out the best in my music collection. The build quality of the SP3000T is outstanding, with a sleek and durable design that feels premium in hand. The intuitive user interface makes navigating through my music library a breeze, and the responsive touch screen enhances the overall user experience."
End Game DAP…for now.
"I decided to acquire the SP3000T as an upgrade to my SP2000T. I can honestly say that the SP3000T is a worthy upgrade in every way. The build quality is superb on both units, but that is where the similarity ends. The SP3000T’s user interface is a HUGE improvement over its predecessor. I have a very large music library of mostly hi-def files and have a 1tb micro sd card installed in addition to the 250gb internal storage. The SP3000T recognizes and loads this massive amount of data in under 30 seconds as opposed to much longer with the SP2000T, just as one comparative example. The sound quality is simply amazing and the new Raytheon vintage tubes are a noticeable improvement over the Korg NuTube in the SP2000T. From the improved CPU to the latest AK DAC chips, the SP3000T is a killer DAP which allows a degree of sound customizations not found in any other product. Anyone looking for a TOTL DAP on the cutting edge of what is possible today will not be disappointed in the SP3000T. At least until the next iteration comes along! 😁"
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