ATOLL PR400 Signature Preamplifier

The PR400 Signature operates in dual mono with one low-noise transformer per channel. The potentiometers and selection relays are also separate for the two channels. The link capacitors (top-of-the-range MKP) are shielded in independent formwork to avoid any parasitic noise. The volume is managed by two motorized, independent, and perfectly synchronized ALPS potentiometers. We use a proprietary servo system, based on a real-time measurement not intrusive to the audio.

The discrete component audio stages have a purely symmetrical structure, the scheme is based on a dual input differential pair and an original scheme biased in class A with very low feedback. This structure allows for the minimisation of both the overall and the intermodulation distortion, which favours the spatial and material perception of the instruments. The PR400 Signature has a low-consumption OLED model display that was chosen for its excellent contrast and low electromagnetic interference. Moreover, its power supply and the ones of all the control devices are completely independent of the audio power supplies.


  • 10 mm brushed aluminium front panel.
  • Linear power supplies based on low-noise toroidal transformers.
  • Symmetrical stages with discrete components.
  • Optional DAC board: DA200.
  • Low-consumption OLED display.
  • ATOLL global remote control.

  • Analog power supplies: 2×10 VA
  • Digital power supplies: 10 VA
  • Total of capacitors: 112 000 µF
  • Number of inputs: 5 lines, 2 XLR
  • Bandwidth: 0,5 Hz – 780 kHz
  • Rising time: 0,4 µs
  • Input Impedance: 357 kΩ
  • Sensibility: 4 V
  • Signal/Noise ratio: 100 dB
  • Distortion at 1 kHz: 0,004%
  • Dimensions: 440×370×130 mm
  • Weight: 15 Kg
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