The new Atoll PR400 Signature preamplifier works in double mono, one low noise transformer per channel. The potentiometer, regulator, input, and output relays are also separated. Each input capacitor is shielded in a metal box linked to the ground. They are a total of 55'000µF per channel. The ALPS potentiometers are controlled by the microprocessor separately. Audio stages are based on discrete components schemes with low feedback.

The PR400 Signature uses the new OLED display.

The concept of rigorously symmetrical stages provides a very detailed and full of nuances musicality with a clear ability to separate the interpreters and the different registers.

The PR400 Signature also has the faculty to present a seamless musicality regardless of the listening level. The care taken to lower settings and the choice of components allows making perceptible the slightest breath and the intentions of the interpreters with a no-brainer and a surprising natural. The smallest nuances and the subtleties of the timbres are perfectly intelligible.