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Atoll Electronique PR400 Evolution
The PR400 EVO is the latest generation of our high-end preamplifier. The IN400 EVO inspires its design.
Its power supplies and electronics have been reworked to significantly improve audio performance. We’ve added the ability to rename the inputs and select the standby mode: Low Power or Preheat. It operates in dual mono (one low-noise linear transformer per channel) and pure balanced. The selection relays are also separate for the two channels. The coupling capacitors (high-end MKP) are shielded in independent enclosures to avoid radiation issues. Volume is controlled by two independent and perfectly synchronised ALPS motorised potentiometers. We use a proprietary servo system based on non-intrusive real-time audio measurement.
- 10 mm brushed, micro-blasted, and anodised aluminium front panel, with high-precision engraving.
- Machined aluminum heatsinks and knobs.
- 2 mm steel chassis.
- Four toroidal transformers: 2 x 10 VA (audio) + 10 VA & 1.6 VA (logic).
- High-quality shielded MKP coupling capacitors.
- Full dual-mono structure:
– Two toroidal transformers: One per channel.
– Four independent audio stages, perfectly symmetrical structure.
– Two motorised ALPS potentiometers: One per channel. - Bipolar transistor input stages.
- Bipolar transistor current sources and LEDs.
- Perfectly symmetrical audio stages with very low feedback.
- Precise balance adjustment.
- Input renaming is available.
- Sleep mode selection: Low power or preheating.
- Adjustable button backlighting.
- High-contrast OLED display: ON or OFF (after 5 seconds of inactivity).
- ATOLL global remote control is included as standard.
- The PR400 EVO can accommodate the following optional boards:
– DAC: DA100 and DA200.
CONNECTIVITY
Inputs
5 Line Inputs: AUX, CD, TUNER, DVD, TAPE.
2 Stereo XLR Inputs.
1 BY-PASS Input.
Outputs
1 TAPE Output.
2 XLR Outputs.
2 Stereo Line Outputs.
1 12V Trigger Output.
1 Ø 6,35 mm headphone jack output.
Various
Possibility of adding DA100 or DA200 digital boards (optional).
The discrete audio stages feature a purely symmetrical structure, with a circuit based on a dual-input differential pair and an original Class A biased circuit with very low feedback. This structure includes perfectly stabilised current generators based on transistors and LEDs, minimising overall and intermodulation distortion. When listening, this enhances the spatial and physical perception of the instruments. The display is a low-power OLED model chosen for its excellent contrast and low electromagnetic radiation. Furthermore, its power supply and control devices are entirely independent of the audio power supplies.
WATT RECOMMENDS
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Professional Reviews 92/100
Deliciously Crispy
Sound Quality
93/100
Build Quality
86/100
Features Connectivity
90/100
Value for Money
94/100
The transparent PR400 Evolution vanishes into the system with a clean, natural balance that Part Time Audiophile found remarkably close to a straight wire with gain. It delivers superb left-to-right imaging, strong width and depth, and a silent backdrop, while balanced XLR connectivity and optional digital expansion add real flexibility for serious systems.
What Reviewers Are Saying
Pros
Exceptionally transparent and unobtrusive, preserving the music without obvious tonal coloration.
Produces a spacious presentation with superb left-to-right imaging plus convincing width and depth.
Flexible connectivity includes balanced XLR and single-ended RCA inputs and outputs, with optional digital expansion available.
Strong value at its price level, with the review calling it worth every penny.
&
Cons
High gain can limit usable volume-control range with some amplifiers, making system matching important.
Front-to-back imaging was good but not the very best the reviewer had heard.
SOUND QUALITY PERFORMANCE 93/100
Reviewers describe the PR400 as exceptionally unobtrusive and close to a straight wire with gain, with a direct path to the speakers and a very low apparent noise floor. Its tonal presentation is described as 'just right' rather than dry, wet, bright, or clinical, and it preserves clean attack and decay with strong width and depth, though one reviewer felt front-to-back imaging was not the very best heard.
Transparency Resolution
97/100
The strongest theme in the review is how little the PR400 seems to add of its own. It is called 'basically invisible' and 'the closest thing' to a wire with gain that the reviewer has experienced, with music taking a direct path to the speakers.
Tonal Balance Musicality
93/100
The tonal balance is praised for avoiding extremes: it is 'not dry', 'not wet', 'not bright', 'not clinical', and 'not boring.' That 'just right' description suggests a very natural, easy-to-live-with character without obvious colorations.
Dynamics
90/100
The review points to convincing attack and decay on percussion and a presentation that feels lively enough to engage, rather than compressed or flat. There is a note about high gain limiting usable volume range on some amplifiers, but not a complaint that the music itself lacks drive.
Soundstage Imaging
91/100
Soundstage width and depth are clearly praised, and left-to-right imaging is described as superb. The only caveat is that front-to-back imaging was not the best the reviewer had heard, which keeps this from reading as universally top-tier spatially.
Assessments of Build Quality, Usability, and Overall Propositions.
Build Quality
86/100
The review calls it a solid-state unit and notes an unconventional but elegant chassis shape, suggesting thoughtful industrial design. However, there is little direct commentary on internal construction, parts quality, or long-term robustness beyond the general impression of a well-made component.
Features Connectivity
90/100
This is a fully balanced preamp with both XLR inputs and outputs, plus single-ended RCA connections as well. An optional digital board adds USB, optical, coaxial, and Bluetooth, and that level of connectivity gives it a clearly more flexible feature set than a basic line stage.
Value for Money
94/100
The reviewer is explicit that the $6600 asking price is more than justified, calling it 'worth every penny' and 'highly recommended.' The phrasing 'some would say ... an insanely good bargain' shows strong value enthusiasm relative to its class and price.
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- A Tube High Fidelity — in-store — Almere, Flevoland, Netherlands (website)
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- Akustik Strauss — in-store — Garmisch-Partenkirchen, Bayern, Germany (website)
- Alpha High End — online and in-store — Brasschaat, Vlaams Gewest, Belgium (website)
- AM Audio Design — in-store — Beauvais, Hauts-de-France, France (website)
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- Ars Antiqua Audio — in-store — Boadilla del Monte, Comunidad de Madrid, Spain (website)
- Art Sonique — France (website)
- Audio Alternative — online and in-store — Fort Collins, Colorado, United States (website)
- Audio Ark — in-store — Edmonton, Alberta, United States (website)
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