The SP4000 platform meets four JAN6418 vacuum tubes
Astell&Kern SP4000T brings the T-series concept to the current flagship platform, combining AK4499EX conversion, four Raytheon JAN6418 tubes and three valve operating modes.
It is the A&ultima model for listeners who want to adjust more than gain alone and actively shape the amplifier's character. Compared with SP4000, it places greater emphasis on valve flexibility: Triode, Ultra Linear and Pentode alter the way the tubes operate, while the Triple AMP system switches between OP AMP, TUBE AMP and a hybrid configuration.
Key features
- Four Raytheon JAN6418 valves in a Quad Tube configuration.
- Three valve modes: Triode, Ultra Linear and Pentode.
- Triple AMP System with OP AMP, TUBE AMP and HYBRID AMP.
- Two AK4191EQ and two AK4499EX devices for digital-to-analogue conversion.
- High Driving Mode, ESA and Advanced DAR.
- Handles PCM through 32-bit/768 kHz together with native DSD512.
- 256 GB internal storage, microSD up to 1.5 TB and full Android.
- 7,450 mAh battery with USB PD 3.0 charging.
Three ways to operate the valves
Control extends beyond the amount of tube contribution. Selecting Triode, Ultra Linear or Pentode changes the JAN6418 operating mode and provides three distinct analogue presentations. Tube current can also be adjusted over three levels, giving a further way to tune energy density and drive behaviour for the connected load.
From solid state to valves in one player
The Triple AMP System can run the op-amp stage alone, engage the tubes or combine the two. This is the principal distinction from SP4000: the latter concentrates on the linearity and drive of its Octa Audio platform, whereas SP4000T adds an adjustable analogue stage for listeners who want to choose a different tonal presentation.
Drive, streaming and portable storage
Connections comprise 3.5 mm unbalanced and 4.4 mm balanced outputs, with High Driving Mode providing extra reserve for more difficult headphones. Full Android supports music applications, while 256 GB of internal storage and microSD expansion accommodate a substantial local high-resolution library.
Headphone matching and use
SP4000T is intended for high-end headphones and IEMs when the user wants to compare a cleaner solid-state presentation with valve alternatives without adding an external amplifier. SP4000 is the direct choice for those who will not use tubes, while SP3000T is the earlier and more compact valve-based alternative.
