Atoll IN 400 SE Review

Atoll IN 400 SE Review

Its great power and its incredibly fast, precise and open sound have already "saved" many speakers that sounded a little limp and regularly amaze visitors: That's exactly how it is. The IN 300 is a cracker. And while I was really raving about it in a larger group, Frank Urban comes from the local Atoll sales department ( Audium) and says: "You have to hear the Atoll IN 400 SE. The IN 300 has no chance against him.” Excuse me? That's hard to imagine.

You can expect a lot from every Atoll amplifier. I have yet to hear a chain with Atoll amplification ( there were a few set up at the HIGH END 2019 as part of the Sounds Clever campaign ) that these French amps did not surprise me in a positive way. Developer Stephane Dubreuil seems to have found a conclusive way to make even his cheap amplifiers sound absolutely convincing.

But now we are at the flagship Atoll IN 400, or rather its current SE version, which has been warming up in the listening room for weeks now and still makes me quarrel about whether there is an amplifier with the front tapering upwards and no other on top (classic) hi-fi finds a.) pretty and b.) can be useful. To save the Atollers' honor, it must be said that there is the CD player in the series, which continues the front line of the amplifier upwards. Nevertheless: This design takes some getting used to.

The self-explanatory operation does not take any getting used to. No wonder: the soul of the IN 400 SE is a purely analog integrated amplifier. There is a USB input (type B), but that should be understood more as an alibi; it's a nod to all those who want to connect at least one digital source.

However, this USB input has nothing to do with the quality that the 400 offers in all other areas. If you want to fully exploit this amplifier digitally, you need an external DAC. And if you want to experience phono at the highest level, you need an external phono stage. 

This consistency is also evident when looking under the hood, where clear order and the shortest signal paths determine the picture.

The structure of the Atoll IN 400 SE

First of all, it is - as befits an amplifier of this class - extremely solid (weight: 19.0 kilos) and consistently designed as double mono: The eight output stage transistors per channel are lined up neatly on each side, each channel has its own own (by the way provided with a special gold coating) circuit board and even the volume control (is implemented via an analog resistor network) is strictly separated into left and right. Only the large mains transformer is only available once, but has - of course - two taps.

MOS-FETs are used here as transistors in the output stage. MOS-FETs are voltage-controlled like tubes, while "normal" transistors are current-controlled. In general, MOS-FETs are considered to sound "warmer" - not least because of this, the developers at Accuphase, Yamaha or even the amplifier legend Nelson Pass swear by these semiconductors. And what Stephane Dubreuil also copied from Nelson Pass is the very cautious use of negative feedback. We find them in the atoll IN 400 SE mainly locally; the overall negative feedback is correspondingly low.

Atoll amps are generally quite powerful, and the IN 400 SE is even more so. With more than 150 watts sinus at 8 ohms (300 at 4 ohms) per channel, it can move a lot. For the developer Dubreuil, however, the waste heat is also a major concern. And if he has to buy special, outrageously expensive mica discs specially made in Japan, then that's fine with him. The entire IN-400 structure follows a clear ventilation concept - with the result of a stable thermal microbehaviour of the output stage. Maybe this is one of the reasons why the Atoll IN 400 SE sounds so good...

And a bit more of the Atoll philosophy: it was important for Dubreuil to give the IN 400 SE a fast-switching power supply. Power supply capacitors stabilize the current through their storage effects - the larger they are, the higher the storage potential. The downside: The larger they are, the more sluggish they become and the filter effect for harmonics decreases. In the Atoll IN 400 SE there are therefore several small and therefore faster filter banks that are connected in parallel.

The hearing test...

I have already mentioned the tonal merits of the IN 300 . His speed and impulsive precision are just great. Salesman Frank Urban was nevertheless right: the bottom line was that the little one had no chance. Because the IN 400 SE adds some warmth in the basic tone range to flawless speed, as well as unbelievable nonchalance and calmness over the entire playback. The triangle sounds a touch finer, voices have more power, classic instruments such as violins and guitars have much richer timbres and the plasticity of the reproduction increases with the IN 400 SE. With the almost always used reference title “Crying”by James Blood Ulmer, the live recording clearly gained in intensity; the big atoll gave us the impression that we were a little bit closer to the live demonstration. And then the cymbals swing a little longer, finer and more naturally...

So this comparison was decided. The IN 400 SE is the even more powerful, yet more sophisticated, you could say more audiophile version of the IN 300 .

That's why another amplifier in this price range, which also plays very finely, had to enter the ring. The Cambridge Edge A is also Subwoofer mania's reference and, among many other advantages, has a wonderfully fine and transparent reproduction. Precisely swinging guitar strings, bright-sounding glockenspiel, working out the finest details from large orchestral works - that is the world of the Edge A . And there it is unquestionably superior to the IN 400 SE.

The atoll has more power from below for that. The comparison with a 12-cylinder engine suggests itself: lots of torque. You may not be the fastest on the Autobahn, but you're pretty quick at traffic lights. That power is impressive. Anyone who enjoys electronic music à la Yello or Infected Mushrooms and their rich electro beats will find it difficult to resist the unbridled power and joy of playing of the Atoll - provided they have the right loudspeakers.

Another integrated amplifier that stays with us, the Neukomm CPA155S, plays at least as precisely and powerfully as the big Atoll, but has less charm in the voice ranges than the Frenchman. Overall , the Atoll IN 400 SE, with its powerful, audiophile nature, reminds me more of the outstandingly good Hegel H590 . Although it brings almost twice the performance, it is also more than twice as expensive...

By the way: During the listening tests, I easily hooked up a dozen different loudspeakers to the Atoll IN 400 SE and none of them - neither the very quiet TAD Compact Evolution One nor the electrically very demanding Canton A55 - somehow let it get out of step. no This amplifier sounds exceptionally good and manages the art of converting this good sound to every speaker. A rare ability.

Conclusion Atoll IN 400

Developer Stephane Dubreuil did nothing revolutionary with the IN 400 or even invented anything new. He merely bundled his knowledge, carefully selected all components and put them together just as carefully. The result was no miracle of equipment, but one of the best, if not THE best integrated amplifier under 5,000 euros. Sonically precise, natural and powerful, but at the same time pleasantly calm. And the IN 400 SE always conveys the reassuring feeling of having enough power under the hood for every situation and every speaker. A very strong recommendation.