Head Box RS is a reference quality headphone amplifier with fully balanced tube input stage (double triode tube 6922) and single ended, class A „FET (Field Effect Transistor)“ output stage. It offers balanced and unbalanced input as well as balanced and unbalanced bypass connectors for using the pass-through input signal with other components. Volume control consists of a precise volume regulator with matched resistance between left and right channel. A special output impedance selector allows to adjust output impedance in three steps 5, 20 and 50 ohm to achieve better impedance matching between amplifier and headphones. Some experiments with different positions of output impedance selector are highly recommended to get the ultimate sound experience for your headphone. An advanced multi-stage power supply with four different output voltages is used to achieve the best possible S/N ratio for outstanding reproduction of detail, dynamics and imaging with any dynamic headphone!

Additional information
Weight2.15 kg
Dimensions20.9 × 20.6 × 7.2 cm



  • Fully balanced double mono design
  • Tube input stage
  • Class-A FET output stage
  • Switchable output impedance for top performance
  • Superior low distortion
  • Low noise components for ultimate dynamic & detail
  • Output: 6.3mm socket
  • Full metal casing in silver or black
  • Upgrade path: Power Box RS Uni 1 (or 4) for further improved sound quality
  • Handmade in Europe


  • Power output: 350mW at 32 ohms / 60mW at 300ohms
  • Crosstalk: -58dB
  • Frequency response: 20Hz – 20kHz/(+0,2dB; -0,05dB)
  • THD+N: 0,17% (XLR in, output impedance setting 5 ohm, load 32 ohm)
  • Gain: 9dB
  • S/N ratio: 99dB
  • Headphone jack: 3-pole ¼“ (6,3mm) co-axial jack
  • Line-level input: 1 pair RCA + 1 pair XLR
  • Line-level output: 1 pair RCA + 1 pair XLR
  • Outboard power supply: 20V/3A DC, suitable for your country’s mains supply
  • Power consumption: 1,3A DC

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