hARt Lab Tune Four Superior Preamplifier

hARt Lab writes: “hARt Lab Tune Four stereo tube preamplifier with streamer, DAC, MM/MC phono input and headphone output builds upon Tune Two and takes further the listening experience to an even superior level. The best volume attenuation technology with the best elements and the unique topology with double tubes deliver an enhanced audio signal able to drive any combination of cables and power amplifiers. And it also provides all modern facilities with multiple options for digital and analog playback.” 

Designed around a single Class-A tube amplification stage with the best components of the current audiophile production. The selection has occurred after extensive listening sessions and with no cost restrictions. With the additional paralleled tubes Tune Four launches the performance to dizzying heights. With great looks and simplified control, using any modern web browser, this preamplifier will offer you a true audiophile experience.
User can select one of the 15 available colors that match to his ambient aesthetics or even turn completely off.
Simple Unified Management. Tune Four is controlled from any modern web browser running on any device, such as smartphone, tablet, pc etc.
Standard infra-red remote controller for the main functions.
Build-in media player with wireless and ethernet connections, integrated functions and adjustments for digital audio and USB ports for external HDD/USB-stick.
Integrated DAC with coaxial and optical inputs, where the signal is being bit-perfect sample rate converted and re-clocked for optimal performance.
High Output Drive Headphone Amplifier. Tube-MOSFET, Class-A hybrid design for superb sonics.
Fully configurable Class A phono stage for MM and MC cartridges. All active discrete circuitry design for excellent accuracy.
A plethora of analog and digital inputs for maximum convenience and functionality.
Amorphous wooden fiberboard chassis dampens unwanted vibrations and mechanical noise feedback, resulting in lower noise floor and eliminating crosstalk.
High End luxury painting procedure MlCoat. Ultra-refined multiple coats of paint, offer a resistant and smooth surface.
Removable side panels for individual appearance, by changing color and/or material.
Fusion of production methods, subtractive manufacturing (CNC) and additive manufacturing (3d-printing), along with a mix of materials (wood, metal, plastic, rubber), allows for stunning looks and launches unrivalled music playback.


  • Use of twin vacuum tubes in a TiPD circuit for superior performance
  • Single Class A tube amplification stage with 4 CV181 (or equivalent), light polarized and without any feedback provides excellent linearity and superior sound. Paired with a Class A tracking buffer forms a hybrid path, which enhances the driving capabilities without compromises, for any power amplifier and interconnecting cables.
  • Alternative direct tube output for pure signal and ultimate performance.
  • Battery emulator VirtAccu with 12 individual, fully separated power supplies for digital audio, analog audio and digital control.
  • Dual mono audio configuration with GroundStar single common earth point for total immunity from mains noise and ground loops.
  • SymLad relay based attenuator with 64 steps of 1 dB provides constant input impedance and achieves zero tracking error and crosstalk between left and right channels, which results in an exceptional soundstage.
  • Acrylic back panel with backplane source switching for minimal audio path.
  • Suspended power supply attachment effectively decouples power transformers from sensitive audio circuitry.
  • FloatOn integrated anti-resonance feet for quieter background and extended sound dimensionality.
  • Inputs: 4x line level, 1x phono, 1x media player (with WLAN, LAN and 3 USB ports), 1x digital coaxial and 1x optical 
  • Outputs: 1x hybrid, 1x tube direct and 1x headphone 6,35 TRS 
  • Phono settings: Gain: MM: 40 dB, MC: 66 dB. Load, resistive: 47 kΩ, 470 Ω, 220, 150, 100, 82, 70 and 60 Ω and capacitive: 100, 250, 330, 430 and 480 pF
  • Line level gain: 21 dB
  • Frequency response: 5 Hz – 140 kHz 
  • Recommended load Hybrid: >16 Ω, Direct: >30 kΩ, Headphones 16-600 Ω 
  • Power consumption: 2 W standby, 60 W idle 
  • Net dimensions: (HxWxD in mm): 200 (with cover) x 430 x 390 (incl. jacks), weight: 12 kg 
  • Shipping dimensions: (HxWxD in mm): 310 x 550 x 490, weight: 22 kg