Atoll IN400 Evo Amplifier

Atoll’s IN400 Evo amplifier replaces the previous IN400 Signature iteration, not surprisingly, the acronym “Evo” stands for “Evolution.” Compared to the previous model, the aesthetics have radically changed in favor of a more conventional, albeit highly polished, presentation. What has not changed are the main nameplate data and weight: nearly 20 kg for a power output of 300 watts per channel into 4 ohms. In its basic configuration the IN400 Evo integrated amplifier is equipped with several analog inputs, but a phono and a digital card are also available for those who wish to further expand the possibilities of this fine French integrated amplifier.

A few words about Atoll Electronique

I begin this review by admitting that I had not had the opportunity, until now, to become better acquainted with this French brand that boasts a very wide, comprehensive catalog full of very interesting proposals. In fact, alongside high-end full-width separates, there is a range of compact units, one of “all in ones,” and then DACs, streamers, phono preamps, and a staggering amount of CD players. Atoll Electronique was founded in 1997 by Stephane and Emmanuel Dubreuil in Brécey, Normandy, with the aim of going to preside over a market segment that was undiscovered at the time, namely that of high-end audio products offered at reasonable prices to budget-conscious audiophiles. The first products began to be put on the market in 1998, immediately gaining a good commercial response, so much so that in 2001 the company needed to move to larger premises. As the only French brand to have Dolby and DTS licenses at the time, Atoll devoted a lot of energy to developing home theater products with a three-year research program that culminated in 2004 with its first multichannel system. In 2016 there was a further expansion of the production facility to meet growing demand, so Atoll Electronique was able to keep both research and development and production in-house.

Atoll IN400 Evo amplifier: external description

Two aspects struck me on first contact with the Atoll IN400 Evo: the first, as already mentioned, is the weight that makes it at least difficult to extract the product from a packaging that is itself of a rather unusual shape. The second aspect that struck me is the large number of analog inputs on the rear panel: as many as seven between XLR (2) and RCA (5), to which must be added the tape loop, pre-out (2) and a bypass. To these should then be added all the digital inputs in case the optional module called DA200 is installed. This boasts two coaxial (24 bit/192 kHz), two optical (24 bit/192 kHz), a Bluetooth receiver and a USB-B port. The module mounts an AKM-AK4493SEQ chipset and can handle PCM up to the maximum resolution of 384 kHz at 32 bits and DSD 256. Installation of the board is not particularly complicated: it involves removing the top panel of the amplifier, removing a rectangular metal cover from the rear panel, placing the module and securing it with the supplied screws, and–not exactly a smooth operation–inserting a small flat into the corresponding connector located on the main board. Simpler, on the other hand, is the installation of the P100 Phono module, which requires only intervention on a bank of Dip Switches so as to transform the Aux input into a Phono input. On the P100 module it is possible to intervene, again using Dip Switches, to specify which type of phono cartridge is in use (MM/MC) and to adjust its electrical load. Finally, a note of merit goes to the connectors for the speaker cables: beautiful and very well made, they are able to accept cables terminated in any way, ensuring a stable and durable connection.

We now turn to the finely brushed, micro-blasted and anodized aluminum front panel, a full 10 mm thick, embellished with the Atoll logo and an ornamental pattern engraved with high precision. A beautiful high-contrast OLED display stands out in the center, giving an account of the selected input and volume level. Available finish options are brushed aluminum anodized in black or silver. Very nice are the two volume and input selector knobs, the circumference of which can be illuminated by LED backlights with a choice of color (blue, red, purple, etc.). In contrast to similar solutions implemented on products from the Far East, here it all results in an understated and elegant effect. The cabinet is made of 2mm-thick powder-coated steel, while the side heatsinks are machined from a block of aluminum hollowed from solid to absorb mechanical vibrations and ensure perfect heat dissipation. The Atoll’s “global remote control” is included as standard, although only part of the buttons are dedicated to the amplifier, while the rest can control an entire Atoll system. There is a 6.35 mm headphone jack on the front panel, which is another nice addition.

Atoll IN400 Evo amplifier: technique

Once the top panel is removed, the internal view reveals the presence of a huge 1050 VA toroidal transformer dedicated to the audio sections, flanked by a series of filter capacitors totaling 96,680 µF. An additional smaller 1.6 VA toroidal is dedicated to the control logic. The overall layout is Dual Mono starting with the transformer, which has separate windings for the two channels, and ending with the two Texas Instruments switching resistor ICs for volume control. Operation is Class AB with a mild rate of feedback. The construction is all discrete components. The input stages of the Atoll IN400 Evo integrated amplifier are based on bipolar transistors, current sources with bipolar transistors and LEDs for voltage stabilization, Darlington transistor driver stages, and audio stages with a perfectly symmetrical structure. The power stages are based on eight MOSFET transistors per channel, selected with great care to ensure strict matching. Particular care was taken in the selection of the material interposed between the transistors and the heat sinks: it is a Kapton/silicon composite that is particularly thermally performate. Also interesting is the solution adopted for the ESA Series Calrity Cap coupling capacitors, which are placed inside a metal case with an insulating function that bears the Atoll logo engraved on it. The input section provides two overlapping and separate boards for the two channels with the connectors directly soldered to the PCB and enabled by relays. I found interesting the ability to choose the standby mode between a low-power mode and one that ensures proper preheating of the amplifier. The right-hand knob is of the multifunction type and, in addition to input selection, allows action on several parameters including the balance between channels that can be memorized.

Listening

Setting up the Atoll IN400 Evo amplifier is as simple and straightforward as it gets. It must be remembered that this integrated amplifier does not have streaming capabilities short of the Bluetooth module. This implies the need to connect to it any analog type source or, in the context of digital streaming, a PC Audio or a pure Streamer connected to the DA200 board in order to start your listening.

We opted for a New Horizon 301i turntable with Ortofon 2M Bronze cartridge in the analog domain, while in the digital domain we connected to the USB input of the DA200 board a DIY Audio PC with JCat components on which Audiolinux was running in Roon Bridge mode. For more critical listening sessions we resorted to our ever-present Aqua La Scala MKII DAC in turn connected to another DIY Audio PC with JCat components on which ran Audiolinux this time in HQPlayer NAA mode. The Server was the Antipodes Audio K30. As speakers we used the Vivid Audio Kaya S12 and, alternatively, the Opera Prima V2. Analog signal and power wiring, as well as power supplies, were Neutral Cable Reference Series.

Reviewing a product like the Atoll IN400 Evo amplifier is both simple and complicated. Simple because, from the very first notes reproduced, one understands that one is before a product made by someone who knows, loves and respects music. This is well beyond what may be the “fundamentals” required of a good audio product, i.e. timbral coherence, dynamics, “stage” spatiality, response extension, etc. All aspects on which the French amplifier excels, without, however, making it stand out (or “weigh”) more. Equally obvious, albeit in a realm of excellence, is “the user experience”: never an uncertainty, never an inconsistency, everything is in its place, that is, where you expect it. There are also no concessions to formal affectation except for the choice of backlight color for the knobs but, believe me, it is something that always moves in the realm of good taste.

No, what is really complicated is to explain, in words, why the sound of this Atoll IN400 Evo is capable of nailing you to a chair in the listening room for hours. You ask yourself as you listen to your favorite tracks, “Why can’t I stop?” The answer is far less obvious than you might imagine, as well as difficult to convey through written text. In a nutshell, I would say that the French amp respects the music. It does not add anything of its own but neither does it take it away. It limits itself (!) to presenting what is written in the recording, to the best of its capabilities which, it should be remembered, are still those of a Hi-Fi product costing just under six thousand Euros. So we are not dealing with a product that belongs to the golden empyrean of the High End, where this kind of approach you expect it, indeed you demand it. Here we are still in economic territory within the reach of many enthusiasts who are eager for a good sound, but who do not want/can’t afford excessive financial outlays, and yet are able to discern a good sound from a sound made to “captivate” or “beguile.” How many times have we found ourselves writing, “The first thing that strikes us about this amplifier is the bass power…” or, “We were shocked by the dynamics of this product.” Kind of like these parameters jumped out of context proposing themselves as the main parameter. Here, with the Atoll IN400 Evo integrated amplifier this never happens. If there is anything to be shocked about-especially in this price range-it is consistency. Simultaneous consistency of all parameters. Let’s take the size of the Stage: listening to the recording of Sibelius’ Concerto in D minor for Violin and Orchestra (Jansen/Mäkela) ed. Decca, not only does the amplitude on the horizontal axis go far beyond the space between the speakers, ideally extending beyond the walls of the listening room, but it is the “filling” that is mind-boggling. In other words: the density of sound on the horizontal (but also vertical) axis is always the same, without any “thickening” that betrays, mercilessly, that we are in the presence of a technological fiction, albeit a sophisticated one. And again: the violin of the sublime Janine Jansen – a Stradivarius I presume – is not played only on the high registers, as is often the case, but through the Atoll IN400 Evo/Vivid Audio Kaya S12 chain acquires a “body,” a mass that makes it much closer to what one might experience if one were to listen to it live than what one usually happens to hear. What about the vocals? For some time now we have been using a fine recording of the duo consisting of Fiorella Mannoia and Danilo Rea on piano. With the Atoll, the singer’s voice becomes full-bodied, less diaphanous than we have experienced lately with some integrated amplifiers passed around the listening room. In a single term: natural.

I would not want you, after reading the previous paragraph, to think of the Atoll IN400 Evo amplifier “only” in terms of refinement: not at all! Let’s not forget that it is a 300 W into 4 ohms (those of the Kaya S12, as it happens…) that, when needed, is able to generate enough pressure to make even the most demanding Rock repertoire credible in such terms. Only, once again, he does so with the gracefulness, theaplomb, that characterizes him. In this case, the fun was to listen to tracks featuring different types of electric guitars (Fender, Gibson, Gretsch, etc.) going in search of their specific sounds. The listening impressions I have just reported concern the configuration that had the Aqua La Scala MKII DAC connected to the line inputs, which is the one that convinced us the most. The performance of the two optional modules is entirely consistent with their price range; perhaps the digital card convinced me more than the phono module, in any case I think they should be considered a good deal from an economic point of view, but not able to extract the full potential of the amplifier.

In conclusion to these brief notes, I would say that my compliments to the Atoll technicians go not only and not so much to the technical solutions adopted, but to the approach held toward the musical content.

Conclusions

What is it that determines whether a product belongs to the High End or not? The price? Well, generally in the common understanding yes, it is the price. However, I like to think that in addition to that, there is also the design approach to the subject of audio reproduction. The respect for music that comes from knowing and understanding it. In this sense, for me, the Atoll IN400 Evo amplifier is a High End product.

Giulio Salvioni

Technical specifications.