Pro-Ject’s Tube Box S2 is our very first product to feature a fully discrete circuit design without using any operational amplifiers (OpAmps).

It also is the first product to come with replaceable tubes for tube rolling and sound-shaping.

This gives the listener many options to pick from and alter the sound signature to their preference.

Tube Box S2 will give a full and relaxed laid back sound with lush mids, just like you would expect it from a much bigger high-end tube phono pre-amplifier. It offers support for both MM and MC cartridges and comes with many gain settings to be switched on the front panel.

Five variable input impedance settings are available to adjust to any MC cartridge, and a 47k ohm input impedance setting is fixed and suited for Moving Magnet and high output Moving Coil designs. The new S2 series aluminum/metal casing protects against vibrations and electromagnetic interference for superior sound.

A true high-end solution in a much smaller package!

Additional information
Weight 0.41 kg
Dimensions 13.1 × 10.3 × 7.3 cm



  • Suitable for MM and MC cartridges
  • Precise RIAA equalization in two parts, passive/active
  • Fully discreet circuit design without OpAmps
  • 2x ECC83 tubes (replaceable)
  • Front-sided Subsonic filter button
  • Front-sided Gain control
  • Ultra low noise circuitry with FET input stage
  • Dual mono circuitry for optimized channel separation
  • Polystyrene capacitors used where possible
  • Gold-plated RCA in- and outputs
  • External power adaptor and multiple internal power supplies
  • Well-filtrated high-voltage anode power supply
  • Sandwich aluminum/metal casing protects from vibrations and electromagnetic interference
  • Available in silver or black
  • Handmade in Europe


  • Tubes: 2 x ECC83 (12AX 7A)
  • Input impedance: 10ohms, 100ohms, 1kohm, 2kohms A,
  • Input capacitance/impedance: 47pF, 147pF, 267pF, 367pF,487pF and 587pF*/47kohms B
  • Input gain: 40dB,43dB B ; 50dB, 53dB and 60dB, 63dB A
  • Noise floor: 80dB (A weighted) at 40dB input gain 75dB (A weighted) at 50 dB and 63dB input gain
  • THD: <0,02% at 40dB input gain <0,05% at 50dB and 63dB input gain
  • RIAA-equalisation curve accuracy: 20Hz – 20kHz / max. 0,4dB
  • Subsonic filter: at 20Hz with 18dB/octave
  • Input: 1 pair RCA/phono sockets
  • Line-level output: 1 pair RCA/phono sockets
  • Outboard power supply: 18V/1.000mA DC, suitable for your country’s mains supply
  • Power consumption: 470mA DC, <1W in standby

A: typical for low output MC cartridges, B: typical for MM cartridges or high output MC
*Input capacitance is irrelevant for low output MC cartridges.


“Sounds fantastic and was a step up (no pun intended) from the solid-state phono preamp built into my Denon receiver” – Caleb Attaway, Analog Planet

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