Head Box RS is a reference quality headphone amplifier with a fully balanced tube input stage (double triode 6922 tube) and a single-ended Class A FET (field effect transistor) output stage. It offers each RCA & XLR (balanced) inputs as well as RCA & XLR outputs for pass-through. Volume control consists of a precise volume regulator with matched resistance between the left and right channels. An output impedance selector allows adjustment in 3 steps: 5, 20 and 50ohm for optimal headphone/amp impedance matching (determine by listening). 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
Weight 2.15 kg
Dimensions 20.9 × 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