Review: Soulnote A-1 Integrated Amplifier

Review: Soulnote A-1 Integrated Amplifier- the Soulnote A-1 is a real sound machine which is more concerned with flow, enjoyment, euphony
4/5 - (4 votes)

Japan – you can associate a lot with this country, but I want to get to something very specific: It corresponds to our idea of ​​Japan when someone dedicates themselves to something in a very special way. And just as with the art of archery Kyudo, a sequence of movements is optimized for life and the ramen cook refines his recipe for decades, there is also this kind of devotion in the audio area.

The head developer of the Japanese hi-fi manufacturer Soulnote ( ), Kato-san, has such dedication – and one fruit of this passion is the Soulnote A-1 (price: 3,590 euros). The integrated amplifier pursues some technical approaches undeterred and with great passion, that alone should pass as “Japanese” in this country. It is also important to mention the “philosophical approach” of the manufacturer, which is communicated in great detail. The quintessence: the sound quality must never be subordinated to technical values.

Soulnote A-1 – technology and equipment

The Soulnote A-1 is a very minimalist integrated amplifier: Three RCA inputs accept unbalanced signals, an XLR double balanced. The selection is made using the “Selector” rotary encoder on the front left, the recess above it is the IR receiver for the included remote control. It goes without saying that the volume and other Soulnote devices can be controlled with the status-appropriate, noble-looking control in addition to the input selection.

If you press the power switch on the left of the front panel, the amp treats itself to an average of 90 watts from the socket, with a maximum of 190 watts. And speaking of the power supply, we need to bring the toroidal transformer into play. The toroidal transformer is located in the middle of the rear part of the housing and has a kind of sub-chassis with its own mandrel – a topic that Kato and his team dedicate themselves to is minimizing resonance. The entire device rests on three spikes, which can optionally be “defused” with flat feet. Speaking of sharpness: According to Soulnote, the resonances of the housing are designed in such a way that they are narrow-banded and therefore easier to control.

According to the Japanese , the secondary voltage leaving the mains transformer is equalized with a particularly fast rectifier diode and smoothed with several low- capacity capacitors operated in parallel. Soulnote emphasizes that these measures mean that the power supply is particularly constant and can quickly provide power for the transistors. 
As always, the amplification power at the speaker terminal varies with the frequency-dependent resistance of the connected boxes: 4-ohm speakers can draw 120 watts per side, 8-ohm speakers 80 watts.

The so-called ” global negative feedback ” feeds the input of an amplifier with a part of the amplified signal – with inverted polarity. What the amplifier adds back to the input signal – the unwanted distortion products – can be reduced as a result. This type of “taming” is used by most manufacturers, but it is – as is well known – discussed critically, because there are also disadvantages.

Soulnote takes a different approach and dispenses with global negative feedback: The A-1 is a non-negative feedback amp. Although you can also read the negative properties of the negative feedback, for example, in the phase response, you do not rely on columns of numbers for the final vote, but on your ears, according to the Japanese. Of course I like that because, as always, I’m looking forward to the most fun part of a test – the long and extensive listening.

Soulnote A-1: ​​Listening Test and Comparisons

Is there anything more obvious with this amplifier than dedicating yourself to the niche of Japanese record productions? Serious tip: if you ever plan to go to record stores in Tokyo, set a budget limit…

The Soulnote A-1 spent a good half of the listening time in the place where the (adjustable) power amplifier Abacus Dolifet 60-120D (currently around 1,400-1,500 euros) normally works. The receivers of the amplified signal were the Harbeth Super HL5 plus XD, the main source being a Merging Technologies HAPI with a “Premium” D/A card. The Soulnote amplifier also went about its work behind the preamplifier of the Rega Mira 3 (around 1,000 euros), directly behind my classic analogue Harrison mixer and in front of various loudspeakers – including the Piega TMicro 5 and JBL Control 1 – during the test period lasting several weeks.

Dynamic impression

Microdynamically, the Soulnote A-1, which amplifies broadband up to 300 kHz, is very fast, but this “speed” never comes across as edgy. The beautifully bubbling ride cymbal or the electric guitar trembling due to the Univibe/Leslie effect on “Omatsuri” (on the prog classic “Ishoku Sokuhatsu” by Yonin Bayashi, 1974), for example, are drawn clearly, but not with “grim” accuracy . For comparison: A Rega Mira 3 almost jovially ignores a few details, and the abacus also leaves something here and there and looks a bit “strained”.

Where some amplifiers absolutely want to display details and get a red head while others are all too laissez-faire, the Soulnote A-1 works with sovereign composure, appears powerful and unerring. The association with Japanese martial arts is not far away: Acting with composure and knowledge of one’s own abilities and using all one’s powers optimally and without waste – that’s how the Soulnote affects me.

The A-1 gently smooths out rough dynamic attacks, but there are no “sags” during load changes. If you don’t want the baroque terrace dynamics like on the BIS recording of the “Christmas Oratorio” by the Bach Collegium Japan under Masaaki Suzuki to be reproduced with great precision, but rather see your amplifier as a “player”, you will be enthusiastic about the Soulnote. The A-1 is less keen on tracing maximum dynamics 1:1 than allowing the flow of the musical event.

I have to give a hint as far as pairing with the speakers is concerned. I often use the beautifully balanced Harbeth speakers, well known in the BBC tradition, for recording, editing and mixing music too. If I want to look for the last detail with a magnifying glass, it turns out that it is quite good if the Harbeths, which are a bit too good-natured compared to current sound engineering monitor loudspeakers, get a – excuse my expression – a kick in the butt from the amplifier. The aforementioned Abacus amp does the job straight forward, balancing my work situation. The Soulnote A-1, on the other hand, like the Harbeth, belongs more to the good-natured, balanced type of audio equipment – and like and like don’t always like to mix. Especially if you want to listen analytically and precisely,

Balanced recordings like the excellently produced 1976 album Mikko  by Yoshiko Sai can also be enjoyed to the full because the soul note manages the balance between nonchalance and precision very well. Less than perfect productions like the song “Mukkaikaze” by Hako Yamasaki are also great fun with the A-1, although the album sometimes has voice bursts and there are other dynamic and spectral inconsistencies. The Soulnote lets that through, of course, but it doesn’t “put a finger in the wound” if you know what I mean.


Striking labels such as “fresh” or “dark” cannot be missed on the A-1, because it simply plays too balanced for that.

The dry bass drum on “Groove is in the Heart” – a piece that made the name of both the group Deee-Lite and the member Towa Tei famous – transports the Soulnote A-1 along with its deep bass components tonally balanced to the Harbeth. And because the great walking bass here is just a sample, I’ll also treat myself to the original “Bring Down The Birds” by Herbie Hancock (listen to the “Blow-Up” album). In the test of the Cambridge EVO 150 (2,500 euros), this bass sounded crisper than the Japanese’s semi-dry, but that didn’t make it any better. The Soulnote A-1 shows once again that “euphony” is not to be equated with “negligence”.

The same play in the low mids: the clear drawing of the guitar in the cover song “Black Sabbath” by the Japanese Flower Traveling Band (Album: Anywhere, 1970) ensures – as with the original Black Sabbath – that the listener gives it their full attention. The simple but iconic one-note riff (prime, octave, tritone) goes through marrow and bone, whereas with the – admittedly also much cheaper – Rega it seems listless and with the abacus a little more “scientific”. A little more with Black Sabbath, which is much more successful in terms of sound-Album than the Japanese emulators, the Soulnote creates a representation that almost wants to let me get into the material. Here at the latest it becomes clear how right Kato-san is: You can’t measure grip and three-dimensionality.

The mids and highs, which Takeshi Terauchi essentially claims for himself on Rashomon in the song of the same name with his surf rock guitar, do not show any abnormalities: the instrument is allowed to spread out in a balanced and uninfluenced manner, the reproduction is extremely linear Only further up the spectrum do I think I can spot a small exception: “Too Many People” (on “Far Out” by Nihonjin, simply meaning “Japanese”) has quite sharp, edgy vocals that can ring in the ears at higher volumes. The Soulnote A-1 is more circumspect here and more benevolent towards this production. However, you have to measure the difference to the somewhat more linear Abacus Dolifet with a letter scale, because it is by no means the case that the A-1 would really intervene to regulate it – it is just a very deliberate moderation of the sharpness.

The highs above the “hiss” frequencies fit into the overall picture of the A-1. The amplifier lets the music material breathe freely. Compared to the Rega, you have the feeling of listening under the open sky without a ceiling. The fact that the tweeter is neither crystalline nor glassy can be easily understood with the Harbeth’s super tweeters. It’s also nice that the air band wasn’t trimmed to ethereal and bodiless at the same time by too high a level, the A-1 simply reproduces linearly and honestly here.

Spatial representation

How concretely the A-1 represents the signals on stage without artificially separating them shows once again that the Soulnote is aiming for balance instead of extremes. The precision and selectivity is basically where that of the Abacus is (a master of the trade), but the breadth and depth of the stage design reminds me more of that of the Rega Elicit MK5 (2,599 euros), which I tested a few months ago had – fits in well with its price range, but is also not the measure of all things. However, the plasticity of the image seems to be a bit higher on the Soulnote.

A little pinch…

The small pinch of overtones that the Soulnote gives to the signal can definitely be recognized, because there is such a light, silky, shiny shimmer … There is a splendor hidden in the signal that is not displayed in a magnificent way, because that would be it much too vulgar for the Japanese.

Sustained tones get a very, very fine structure, percussive parts a short, additional shine. You’ll notice: I have to dig for words to describe it aptly… It seems a little as if the material contains tiny doses of what characterizes some tube amplifiers, but without the often too strong “interventions” by the output transformers. In any case, it turns out that simply keeping distortion products small, come hell or high water, is not the silver bullet for a “nice” sounding amplifier, the equation “distortion = bad” is far too simple. With Soulnote, a small amount of harmonic overtones is apparently used to support the euphony.

Level issues

The sound characteristics of the Soulnote A-1 remain identical over a wide control range, only at very low listening levels does the overall experience seem a bit paler. The wonderful three-dimensionality only comes into its own from a (low) normal level. But who wants to hear a good system at whisper volume?

However, the A-1 is not trimmed for the highest volumes either. With speakers the size and efficiency of a Harbeth, the maximum amplification is certainly suitable for a party, but is below what other representatives of the guild could blow into the room. It seems as if Soulnote deliberately no longer made available the area from which quality losses could occur.

Two things should be mentioned: You don’t appreciate the amplifier if you turn it on, blast it for four minutes of a piece of music and turn it off again. While I don’t believe in souls, sensitivities or states of mind of electronic components, the Soulnote A-1 should be allowed to come up to operating temperature. In the first few minutes in particular, he usually plays almost disappointingly flat, and then his potential is still asleep. Second, both source and level selection are done with relays. This is a commendable thing and serves both the sound quality and the durability, the rich click when shifting underscores this feeling. Due to the principle, the clicks also find their way to the speakers, but I think that’s tolerable.


If you want to trim your system to the most fussy detail display, you will find amplifiers that are better suited for this – the Soulnote A-1 is more concerned with flow, enjoyment, euphony. Actually, I don’t like the term and am always looking for ways to avoid it. But there is no other way, the Soulnote has made it and deserves that I put it this way: The A-1 sounds musical .

In any case, he has softened my sometimes somewhat dry sound engineer soul with discreet charm and character. The minimalistic integrated amplifier has a lot of power, but never flexes its muscles provocatively, it has a certain lightness and draws fine structures, but doesn’t do all this under floodlights or with a toothpaste grin for the cameras. The Soulnote A-1 is an amazing amp.

The Soulnote A-1…

  • puts the musical flow and euphony first. At the same time, the impulse and detail display does not suffer, the music playback always seems slightly springy instead of slowed down. The A-1 is finely balanced in terms of macro and microdynamics – however, it is more convincing in combination with sensitive loudspeakers than with those that literally need a “kick in the butt”.
  • is not a “riot brother” and doesn’t want to be either: High levels are possible, but not exorbitantly high either. On the other hand, it still sounds the same loud as it does in the medium volume range. Only at a very low level does one miss a little of the wonderful liveliness in the sound.
  • is neither dark/warm nor sparkling/fresh. The tonal representation is very balanced overall and plays from the deepest depths to the highest heights without any real preferences.
  • transmits the bass neutrally and with an almost outrageous lightness. The contours are there, but they don’t look dust-dry – a skilful tightrope walk.
  • delivers the mid-range with a certain benevolence, for example when voices or individual components on the recording want to stand out too much from the music. It is therefore positioned somewhat moderately in the sharpness range. This is very good for biting productions, in this regard perfectly mixed and mastered music seems a little (too) mild. My tip: Don’t pair it with speakers that play too softly.
  • has a very open and natural high tone that sounds free but never forced.
  • provides the sound image with a very slight “shine” without being downright flattering or euphemistic.
  • delivers in terms of stage depth and width befitting. Individual instruments and voices are modeled extremely vividly and tactilely in the stage design – that seems to be the more important characteristic in many pieces of music.


  • Concept: integrated amplifier
  • Price: 3,590 euros
  • Dimensions & Weight: 43 x 109 x 418 mm (WxDxH), 10.0 kg
  • Color: Black, Silver
  • Inputs: 3 x RCA pairs, 1 x XLR pair
  • Outputs: 1 x pair of speakers
  • Output power: 2 x 80 watts into 8 ohms, 2 x 120 watts into 4 ohms
  • Miscellaneous: system remote control
  • Guarantee: 3 years