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POWER AMPLIFIER ⸜ monoblocks


Manufacturer: CSR, Inc.
Price (when reviewed): 180 000 PLN/pair

Contact: 33-4, Sagamiono 5 chome
Sagamihara-shi Minami-ku
Kanagawa-Pref. 252-0303 | JAPAN


Provided for test by:


translation Marek Dyba
photos “High Fidelity”

No 229

June 1, 2023

SOULNOTE is a Japanese company founded in 2004 by a former director of Marantz Nippon, an engineer, Mr. NORINAGA NAKAZAWA. It specializes in the designing of solid-state amplifiers, phono preamplifiers and digital sources from the middle and higher price range. We test its latest power amplifier, the M-3 monoblocks. This is their EUROPEAN PREMIERE.


EXT YEAR, the Japanese company SoulNote will celebrate its anniversary - twenty years in business. I don't know if that was the plan or if they are preparing something special for this occasion, but it seems that this will be the year in which her top "3" series, which contains all their knowledge and experience, will be completed. This phrase is used by many manufacturers, not only audio, and it seems to be one of the most frequently used by promotion specialists. In the case of SoulNote, however, it is true.

For a long time known mainly in its native country, and more broadly - in Asia, in Europe it marked its presence only in the second decade. In "High Fidelity" we tested its first device, the 710 integrated amplifier, on May 16th 2014; more → HERE. It seems that the impulse for the leap, the fruits of which we are seeing, was given by employment as the chief engineer of Mr. HIDEKI KATO, which took place in 2016.

As he told us on the occasion of the P-3 preamplifier review, the patron (founder of the company), Mr. NORINAGA NAKAZAWA, commissioned him to do only one thing: he was to make SOULNOTE the best audio brand on the market (more → HERE). And he started with basic devices, such as the A-2 integrated amplifier (test → HERE), and only in 2019 he presented the first device from the top "3" series, which turned out to be an outstanding device, the SACD player S-3, which we tested in the "2" version in 2021 (more → HERE):

˻ 2016 ˺ → A-1, C-1, E-1, A-0
˻ 2017 ˺ → D-1, A-2, E-2
˻ 2018 ˺ → D-2, D-1N
˻ 2019 ˺ → S-3
˻ 2020 ˺ → S-3 ver. 2, P-3
˻ 2021 ˺ → ZEUS (D-3, Z-3, X-3, RCC-1), S-3 Ref.
˻ 2022 ˺ → M-3

Let me remind you that the P-3 preamplifier received the STATEMENT IN HIGH FIDELITY 2022 award, jointly awarded by and "High Fidelity" magazines. Last year they were joined by the M-3 monoblocks, which Mr. Kato presented to me during the 2022 High End Show (more → HERE).


The M-3 POWER AMPLIFIER has the form of two monoblocks, i.e. monophonic devices - two are needed for stereo. Their body has great proportions, and although they are quite large - they measure 340 × 251 × 512 mm - heavy - they weigh 31 kg each - compared to the Soulution 710 amplifier they seem compact. Their front is almost empty, not counting the polished logotype and a two-color LED indicating the operation of the device.

When I found out that this device was going to be built, I thought that its front would look like the other devices from this series, that is with vertical ‘ribs’. As it turned out, I was wrong. The front is perfectly flat in the vertical projection and only in the horizontal projection is it cut into three parts. I asked Mr. Nobumasa, who, together with the company Audiopunkt, distributes these devices in Poland, about it to which he replied that his compatriots do not like exaggeration, they do not like to show off. Hence the flat, ascetic front panel, and only on the sides was added the motif I was talking about.

On the back there is also not much to look at, because there are only speaker terminals and a single XLR socket - M-3 requires a balanced signal connection. A bit of variety is introduced by the sides of the device, on which you can see a large SoulNote logo formed by cooling holes and the aforementioned ‘ribs’. The M-3 also looks nice because it stands on spikes, and we put them on wooden anti-vibration platforms. Knowing their operation from other devices of this company, it seems to me that they should be treated as an integral part of the system.

˻ MECHANICS ˺ At first glance, a classic. The reality is different though: the M-3 is one of the most mechanically complex power amplifiers I've ever seen, perhaps even the most complex one. All sections of the device are physically separated from each other. Both the electronics boards and the side baffles, bottom and top, transformer and power supply - each of these elements is an independent whole that only "lies" in a given place and is not permanently tightened to anything. Also the aluminum plates on which the loudspeaker terminals, separate XLR input and - on a separate plate - the power socket are installed, are independent of each other and "floating". To keep it from falling apart, everything is mounted on pins with titanium washers.

Vibrations can be extinguished by turning them into heat already in the amplifier, but you can also send them outside and lose their energy there. The platforms SoulNote devices are sold with serve this very purpose. They just seem to be boards glued together from wooden slats, with a cutout in the middle. They are something more though. As Mr. Kato says, he spent a lot of time to choose their size and the size of these holes, to choose the resonant frequency of the system so that the sound was as good as possible. So he approached this problem more like a luthier than an engineer.

The platforms in question in the case of the M-3 are much larger than the outline of the amplifier - they measure 66 x 45 cm and, through metal pins, rise above the floor to a height of 8.5 cm. The system of removing and reducing vibrations is based on spiked supports, which we usually refer to as "spikes". In the M-3, individual sections, such as the power supply, output transistors, etc., are decoupled separately, because they are mechanically separated, independent. So there are six spikes underneath, not three or four. Templates are attached to the amplifiers, thanks to which we place the device exactly where the designer intended it.

˻ ELECTRONICS ˺ Although the mechanics of the M-3 are stunning, interesting things can also be found in the belly of the beast. The amplification circuit is based on a pair of Darlington transistors working in a push-pull configuration, placed in metal TO-3 cases, which have not been used for a long time. High power requires the use of many parallel connected transistors. It's a simple and easy way, provided that we match them all with super precision so that they have exactly the same characteristics, and then compensate for the differences that remain. Reducing the amplification circuits allows you to avoid problems with their evaporation. Let me remind you that the Japanese Denon has been doing this for years.

The M-3 uses NOS Darlington transistors with worn off markings. Similar models once produced by Motorola now cost over PLN 500 per unit. Although they look like a single transistor, they are several Darlington transistors. A "Darlington" (or "Darlington transistor") is an arrangement of two or more - here four - transistors offering high gain. It was developed in 1953 by Sidney Darlington at Bell Laboratories, hence its name. It has its problems, but its main advantage - high power - is hard to overestimate. The more so that it is achieved with a very short signal path.

The transistors in the tested amplifier were bolted to huge copper plates. Since the TO-3 chassis had bottom exits, SoulNote took advantage of this to bypass the wiring and solder it directly to the amp’s board. As we read in the company materials, it eliminates the problems with parasitic capacitance, which arises with the inevitable deterioration of the mechanical properties of the pads under the transistors - here they are screwed directly to copper bars, which are part of the electrical system.

When designing the M-3, one of Mr. Kato's priorities was a short signal path. Therefore, the voltage (input) circuit works without feedback and consists of one stage, and the latter of four transistors. The manufacturer describes this solution as follows:

Only a single transistor is used to fully amplify the emitter follower, voltage, and differential circuits without any gain. The load impedance in this transistor is a "GND one-stage amplification single-end non-NFB circuit" that connects only to the GND. These new Type-R circuits were created using only 4 bipolar junction transistors and 10 resistors to extract ideal full swing output across a wide spectrum, even though this configuration is primarily the same as that used for single ended tube amplifiers. This ideal non-NFB circuit could easily be dubbed a reference circuit (for other manufacturers - ed.) for how well it performs.

The signal from preamplifier is fed to a single XLR input - there is no separate RCA input. Press materials say that the idea was to eliminate all switches from the signal path.

And finally there is a powerful power supply. Its basis is a 1.6 kW toroidal transformer in a shielded box, flooded with damping material. This one, however, is not the usual epoxy resin, but a different material, not specified by the manufacturer though. The transformer was bolted vertically, parallel to the front panel, so that - as the designer says - the stray field ran parallel to the boards with amplifying circuits. As in other SoulNote devices, instead of a few large capacitors, we have a bank of many smaller ones, with a total capacity of 470 μF. The devices are turned on with mechanical switches that can be found on one of the sides.

Pure perfection down to the last detail.


⸜ HOW WE LISTENED The SoulNote M-3 power amplifiers were placed in the same place as the Octave Jubilee 300B monoblocks, based on three 300B tubes per channel were some time ago, and played in exactly the same configuration (more → HERE).

So the M-3 was compared to my reference amplifier, the Soulution 710 solid-state power amplifier, and drove the Harbeth M40.1 loudspeakers. The initial amplification of the signal was done by the Ayon Audio Spheris III tube preamplifier, but the manufacturer offers its own P-3 preamplifier, which should be the first to try these monoblocks with. The set looks great and performs just as well.

The signal between the preamplifier and the power amplifier(s) was carried in both cases by the XLR Acoustic Revive Triple-C interconnect. The amplifiers were powered by Acoustic Revive Absolute Power cables, but I also tried ordinary Kryna Helco braided cables (test available on May 16th).

The signal to the loudspeakers in my system is carried by the Siltech Triple Crown speaker cable. However, it is very stiff, so for some time in such cases I have been using another, equally wonderful cable - Da Vinci's Crystal Cable Art Series (test → HERE). The signal source was the Ayon Audio CD-35 HF Edition SACD player.

⸜ Recordings used for the test | a selection

⸜ ELGAR, Cello Concerto/Sea Pictures, perf. by Jacqueline du Pré, Janet Baker, London Symphony Orchestra, conductor Sir John Barbirolli, EMI/Esoteric ESSW-90254, „Master Sound Works” series, SACD/CD (1965/2022); review → HERE.
⸜ JOHN COLTRANE QUARTET, Ballads, Impulse!/Universal Music LLC (Japan) UCCU-40001, Platinum SHM-CD (1962/2013); review → HERE.
⸜ NAT KING COLE, Love Songs, ABC (Int'l) Records Master-245A, Master CD-R, review → HERE.
⸜ MICHAEL JACKSON, Thriller, Epic/Mobile Fidelity Sound Lab UDSACD 2251, „Original Master Recording, Ultradisc II” series, SACD/CD (1982/2022).
⸜ KRAFTWERK, Live on Radio Bremen, Philips (?) 2561971, Bootleg, CD (2006).
⸜ NOVIKA, Tricks of Life, Kayax 013 CD (2006) review → HERE


SOME TIME AGO, one of the "High Fidelity" readers sent a rather angry e-mail to the editorial office, in which he reproached us for using classical music too rarely, or even not at all, when evaluating the sound of audio products. I then answered truthfully that our methodology is based on A/B or A/B/A comparisons, and there is no room for long sample material. One, two minutes maximum and switch. Longer fragments make it much more difficult to refer to the differences. And classical music is a sound stretched over time - much wider than in the case of rock, pop or even jazz (mostly).

This time, however, I couldn't start in any other way but with ELGAR and his Cello Concerto/Sea Pictures, performed by Jacqueline du Pré under the baton of Sir John Barbirolli. It so happens that this was the track we listened to with Mr. Kato, the chief engineer of SoulNote, last year during the show in Munich. And we listened to it for a long time. During the gala dinner, during which we presented SoulNote and Børresen with the STATEMENT in High Fidelity award, we started discussing our favorite albums and I mentioned that the latest remaster of the title in question had just been presented by the Esoteric label (more → HERE). To which the SoulNote’s designer added that he preferred the files version, available on the e-onkyo streaming service. So the comparison was inevitable.

I remember those emotions - first of all, because we listened to great music, secondly, that I did it with a fantastic man, and thirdly, it was done in the full SoulNote system. Although neither of us convinced the other, I also appreciated how the file player, the ZEUS system, rendered the beauty of Edgar's cello concerto and how well the P-3 preamplifier and the M-3 power amplifiers delivered this music.

So, I started listening to the SoulNote monoblocks in my system with the same album. My plan was to audition Adagio – Moderato, maybe even Lento – Allegro Molto, and it ended up with the whole concert. The M-3 turned out to be such a good "carrier" for emotions that I listened to the music with interest and commitment, paying attention to the music itself and how it was reproduced.

A it is reproduced in an extremely non-mechanical way. I mean in a natural, unobtrusive way with its "technology" of reproduction. The Japanese amplifier has its own features, we'll get to that in a moment. But it is also part of such an uninhibited, lively presentation. The explosive character of when the orchestra enters, right after the delicate sounds of the cello, was sustained by the SoulNote amplifier and reproduced with exceptional care.

It's a sound presented in an absolutely incredibly effortless way and of an unobtrusive character. In the sense that the sound is presented in a very precise way, both in terms of timing and timbre, but it does not have the effect of "forcing" emotions on us. Listening to another classic, THE COLTRANE QUARTET’S Ballads, in a very good reissue on the Platinum SHM-CD, I entered the same world again. The world of my personal freedom, where I don't have to do anything and I can do everything.

And I could listen in incredible comfort, analyze if I wanted to, or just relax doing something else. M-3s have the peculiar property of changing with our expectations. When I listened to the albums in terms of sound analysis, they allowed me to do so thanks to exceptional resolution and differentiation. When I needed a break, I switched between the two states almost imperceptibly, without being forced or feeling like I was missing something.

The timbre of the amplifier helps a lot. It is creamy and at the same time shaped like Urushi varnish. It is shiny, but shiny with depth, something uneven underneath, and therefore perfect in its naturalness. Which is how this Japanese way of covering wood differ from piano lacquer. Coltrane's saxophone had great depth, it was three-dimensional and even the piano, recorded by Rudy Van Gelder with very closely placed microphones, and therefore a bit "boxy", sounded more free than usual.

On the one hand, the device presents a close foreground, and on the other hand, it does not "close" it in a box, stretching the stage in width and depth. So when NAT KING COLE starts singing "The very thought of you and I forget to do", his vocals are shown right in front of me, close, in an intimate way. However, the accompanying orchestra is far behind and to the sides, not interfering with the voice. The first impression of this track, listened to on a high-end system, is always the same - and it's about the impression of Cole's "presence". After a while, after accommodation, we hear more - just a huge space. From the M-3 it was a perfect transition.

The amplifier perfectly differentiates not only timbre, but also spatial aspects. It also has exceptional dynamics, although it is one not "for show". As I mentioned when listening to Edgar's Cello Concerto/Sea Pictures, the device is fast and the transition between different emotional states is smooth and pleasant with it. But now, with the next tracks from the Love Songs, released on the Master CD-R, it was clearly audible how different reverbs are used for the subsequent tracks of this compilation. The Japanese amplifier never got lost in this and did not blur the differences.

Mr. Kato's devices, despite the fact that they have a lot of output power, do not "pump" the bass, and their tonal balance is selected with sensitivity. The sound, however, is based on the midrange, as is the case with most SET type tube amplifiers. Bass, like in MICHAEL JACKSON's Bille Jean, had great textures, was smooth, dense and warm. But it also did not go as low and did not have the same energy at the very bottom of the band as with the Soulution 710 amplifier.

It was clear that in the M-3 this choice led to smoothness and density, which immediately reminded me of the sound of the Octave Jubilee 300 amplifier, based on 300B triodes. But there's nothing to worry about. There is enough bass here. It has a flawless connection with the midrange, which makes the presentation seem extremely homogeneous, i.e. natural. The low passages of analog synthesizers in the song Heavy Metal Kids, which opened the KRAFTWERK’S recording of the 1971 concert, built a large stage, a strong presentation, not forgetting that it is a live performance, i.e. about an atmosphere and a slight distancing of instruments from the foreground.

All this allows you to listen to music really loud with M-3, and yet you never get tired of it. In fact, the louder it is, the bigger the sound is and the denser the textures of the instruments are. The aforementioned concert happened still at a stage when Kraftwerk played with "live" drums and guitars, which M-3 put together into a dense whole, reminiscent of what Deep Purple was offering at that time.

The electronics from NOVIKA's album Tricks f Life also sounded beautiful. Her vocals were incredibly close, and although there were strong sibilants in it, I did not perceive them as an error, but as a "coloration" preserved by the sound engineer, giving the voice a fresh and open expression. The amplifier precisely arranged the space, in breadth and depth, as it does with all albums. Here it was so strong, so convincing, that I don't remember the last time - apart from the reference system - this album was played in an equally convincing way .


M-3 MONOBLOCKS TURNED OUT TO BE EXTREMELY mature devices. In addition, the ones that play any music with equally great commitment. Whether it's Edgar, or Novika, or Coltrane - it didn't matter what kind of music I listened to, but whether it was good music. It is also the case that the tested amplifier does not emphasize the weaker sides of the particular production. Instead, it likes to emphasize their qualities, good things, advantages. If there is density, we will get density, if there is dynamics, we will get dynamics, if there is an open sound - this is the sound we will get, and actually "more" of everything.

The timbre of the devices is focused on the dense midrange, very similar to what I know from high-end tube amplifiers. The consistency of the sound is maintained, its fluidity and coherence. When needed, the amplifier shows the low bass without shortening or shallowing it - that's why the electronic bass in the title track from the Novika album was so incredibly good.

Ultimately, however, we will return to albums with vocals in the lead role, with dense, jazz guitar, with saturated electronics. The SoulNote M-3 has a human dimension and a human approach to sound. And that's what we need. Hence the ˻GOLD FINGERPRINT award.

Technical specifications (according to the manufacturer)

Maximum output: 160 W (4Ω)
THD: 0.1% (1 W)
Frequency range: 2 Hz - 200 kHz (±1 dB)
Sensitivity/input impedance: 2 V/25 kΩ
Gain: 22 dB
Power consumption: 110 W/36 W (idle)
Dimensions (W x H x D): 340 × 251 × 512 mm
Weight: 31 kg


Reference system 2022

1) Loudspeakers: HARBETH M40.1 |REVIEW|
2) Line preamplifier: AYON AUDIO Spheris III Linestage |REVIEW|
3) Super Audio CD Player: AYON AUDIO CD-35 HF Edition No. 01/50 |REVIEW|
4) Stands (loudspeakers): ACOUSTIC REVIVE (custom) |ABOUT|
5) Power amplifier: SOULUTION 710
6) Loudspeaker filter: SPEC REAL-SOUND PROCESSOR RSP-AZ9EX (prototype) |REVIEW|
7) Hi-Fi rack: FINITE ELEMENTE Pagode Edition |ABOUT|


Analog interconnect SACD Player - Line preamplifier: SILTECH Triple Crown (1 m) |ABOUT|
Analog interconnect Line preamplifier - Power amplifier: ACOUSTIC REVIVE RCA-1.0 Absolute-FM (1 m) |REVIEW|
Speaker cable: SILTECH Triple Crown (2.5 m) |ABOUT|

AC Power

Power cable | Mains Power Distribution Block - SACD Player: SILTECH Triple Crown
Power (2 m) |ARTICLE|
Power cable | Mains Power Distribution Block - Line preamplifier - ACOUSTIC REVIVE
Power Reference Triple-C (2 m) |REVIEW|
Power cable | Mains Power Distribution Block - Power amplifier - ACROLINK Mexcel 7N-PC9500 |ARTICLE|
Power cable | Power Receptacle - Mains Power Distribution Block: ACROLINK Mexcel 7N-PC9500 (2 m) |ARTICLE|
Power Receptacle: Acoustic Revive RTP-4eu ULTIMATE |REVIEW|
Anti-vibration platform under Acoustic Revive RTP-4eu ULTIMATE: Asura QUALITY RECOVERY SYSTEM Level 1 |REVIEW|
Power Supply Conditioner: Acoustic Revive RPC-1 |REVIEW|
Power Supply Conditioner: Acoustic Revive RAS-14 Triple-C |REVIEW|
Passive filter EMI/RFI: VERICTUM Block |REVIEW|


Speaker stands: ACOUSTIC REVIVE (custom)
Hi-Fi rack: FINITE ELEMENTE Pagode Edition |ABOUT|
Anti-vibration platforms: ACOUSTIC REVIVE RAF-48H |ARTICLE|

  • HARMONIX TU-666M "BeauTone" MILLION MAESTRO 20th Anniversary Edition |REVIEW|


Phono preamplifier: Phono cartridges: Tonearm (12"): Reed 3P |REVIEW|

Clamp: PATHE WINGS Titanium PW-Ti 770 | Limited Edition

Record mats:


Headphone amplifier: AYON AUDIO HA-3 |REVIEW|

Headphones: Headphone Cables: Forza AudioWorks NOIR HYBRID HPC