Atoll electronique IN 400 Evolution

The IN 400 Evolution is a stereo integrated amplifier-preamplifier from Atoll electronique, manufactured in France. It succeeds the IN400 Se in the manufacturer's range and is positioned as a model intended for demanding listening, capable of driving speakers directly without an additional power amplifier stage.

Its electrical structure is rigorously dual mono, with a dedicated attenuator per channel and two separate star earths, which limits interaction between left and right channels. The power supply relies on two toroidal transformers, one of 1015 VA reserved for the audio section, the other of 1.6 VA for the control logic, combined with a current storage capacity of 96,680 µF. Each channel carries eight matched MOS-FET transistors, for a stated output of 2x300 W into 4 ohms. Total harmonic distortion stands at 0.05%, the signal-to-noise ratio at 100 dB, and the frequency response extends from 5 Hz to 100 kHz, with a rise time of 2 µs. The 2 mm steel chassis and 10 mm aluminium front panel, together with side heatsinks machined from solid blocks, contribute to mechanical stability and heat dissipation.

In terms of connectivity, the unit offers five RCA stereo analogue inputs (one of which is compatible with an optional phono module), two XLR inputs, a ByPass output, a 12V Trigger output, a front-panel headphone output and two RCA pre-out outputs. It also includes two optical inputs and two coaxial inputs at 24-bit/192 kHz, an asynchronous USB input at 24-bit/192 kHz and a Bluetooth input, allowing the connection of analogue sources as well as digital sources or a portable audio player.

This type of amplifier is aimed at a user who already owns quality speakers and wants a system core capable of delivering substantial power into low impedance, while retaining the flexibility of a multi-source preamplifier. The presence of a dedicated phono module input and multiple digital inputs makes it a suitable base for a mixed setup, combining a turntable, digital sources and Bluetooth streaming.