"The design goal of the AMP-11R is to be a world best high-end compact amplifier."

A bold statement, but ultimately, you have to play to win… The above sentence begins the description of the AMP-11R integrated amplifier, available on Bakoon International website. This amplifier is different than almost all others I have dealt with so far. Its enclosure is made of a single aluminum block with milled in chambers housing various sections circuits. Obviously, we know this kind of design employed e.g. in the top R series from Ayre or – from my Polish backyard – in the unique nowe audio mono 3.5 monoblocks. Maybe it’s a coincidence, but both the amplifier and the RCK-11 dedicated platform are equipped with metal cones yet during the review they ended up instead sitting on the Ceraball feet from German manufacturer finite elemente. But then, on the other hand, there are no coincidences. Even this short introduction shows that we are dealing with a very special product. Coming from Korea, which grows to become a strong player in high-end audio field, it features an outboard power supply and can be placed on a specially designed dedicated anti-vibration platform. The latter consists of two beautifully anodized aluminum panels separated by ceramic balls, used in the aerospace industry. Extending this idea to include the feet (Ceraballs also sport a ceramic ball between two surfaces) seems like a logical step.
However, that is not all. The most important feature of this device is a special electronic circuit called SATRI (SATRI-IC). It’s a current amplifier circuit, developed since the 80s. It’s main idea is to process the input and the amplified signal in the current, not voltage, form. Such a system is best fed with current signal and special BNC inputs are used for that. Other “big names” of audio also used and still use similar solutions. Just to mention CAST (Current Audio Signal Transmission) from Krell, or Zell from darTZell (also on BNC connectors although the input has a different nominal impedance). Here, it’s not only about the inputs and the method of transmission but also a specially designed, surface-mount circuit currently in the new SATRI-IC-EX version. The unit received for this review also sports output modules different from the previous version. Power output of the new amp is 15 watts (into 8 Ω).

It did not immediately dawn on me (which only shows my temporary obtuseness) but it turns out that Bakoon Products International having its registered office in Korea is affiliated with its parent company, Bakoon Products Co. Ltd., a strictly Japanese company. All design solutions found in the AMP-11R, including SATRI, has already been ‘rehearsed” in the parent company. Ms. Chae Soo In, a company representative, just before the publication of this reviews let us know that the Korean branch would soon have new products, previously only available in Japan.
From an interview available on the BPI website we learn that the owner and designer of Bakoon Products is Mr. Akira Nagai. It was he who 25 years ago developed the SATRI system. He was also one of the first designers of a D/A converter in which special attention was given to reducing distortion due to uneven timing, currently known as jitter. That DAC was the first to employ the SATRI system designed to use no negative feedback without adverse consequences such as distortion, narrow frequency response, noise, etc. Where did the name come from? It is not an acronym, as usual, but rather a slightly transformed Japanese word ‘satori’, meaning ‘enlightenment.’ It is worth noting that Mr. Nagai began his audio adventure from tubes of which he was a devotee. His collection consisted of over 2000 items.
For the review I received not only the AMP-11R amplifier with the dedicated RCK-11 anti-vibration platform, but also the EQA-11R phono stage with SATRI output and the battery operated BPS-02 power supply, designed for the Arcam rDAC. Initially, I intended to review all the components from the ‘1’ series together, and separately the power supply (it's a series ‘0’). During the review, however, it turned out that each of these components deserves enough attention to go beyond the scope of a single review. I ended up writing about the amplifier in this first review and planning two separate articles on the preamplifier and the power supply accordingly. Nonetheless, I took a few photos of all the three devices from the ‘1’ series in order to show how they look together, sitting on their anti-vibration platforms.

SOUND

“You see one thing and you hear another” is a common theme in all kinds of audio-visual arts. The element of surprise, catching the viewer/listener off guard, pushing him/her out of their comfort zone is the basic tactics of contemporary performers and stand-up comedians. It is no different in the case of designers, including those in industrial design. For them, surprise is nothing but a way out of the shadow, of a dead end, so to speak. In audio, however, that does not seem to work.
When we think of speakers or amplifiers “bigger” seems to be “better.” The reason for that is that the speaker needs a large woofer (or two) to reproduce low frequency bass and the amplifier needs a powerful power supply, which (except for switching power supplies) means a large mains transformer.
Therefore, when we see such a small amplifier as the one reviewed here, we subconsciously expect suitably “tiny” sound. And, despite my best effort not to sound like a cheesy advertisement I must say that the AMP-11R amplifier is an example of how appearances can be deceptive.
When I first saw Bakoon products at home, I could hardly believe how well finished they were, how well thought out their every detail was. I know how incredible are the challenges that must be faced by an audio manufacturer striving for perfection and how many years it takes to develop a “pattern” of activities, mainly related to working with sub-contractors and components manufacturers.
I got down to auditioning with all the more respect. However, it soon became apparent that my initial “awe” was not necessary and that the device stood up perfectly well on its own and even if it had been packed in a shoe box, its designers would deserve a bow down. The question, of course, is whether it would have sounded equally well housed in a shoe box (no, not really), but it is a discussion for another article.

AMR-11R + speakers

The amplifier connected to matching speakers, more on which later, spreads out in front of us a large, intense sound stage with substantial, almost life-size, phantom images. It is particularly important with mono recordings that usually suffer the most on low-powered amps, with thinned out midrange or soundstage compressed to the size of a keyhole. And that happens all too often, for even the best products, if focused only on accuracy, attack or punch do not sound satisfactory, showing but a general framework rather than the song itself.
The Korean baby, or actually twins as it's a two-box amplifier, sounds remarkably big. It will catch by surprise not only the skeptics but also those who have already heard a lot of amps. Even with the powerful Harbeths M40.1 that require loads of power and get down very low. With the M30.1 that impression was even more intense.
It struck me hard right at the first album I listened to, Love is the Thing by Nat “King” Cole, but was nearly floored – despite sitting on the couch – by the mono, not particularly well recorded album Max Roach and Clifford Brown in Concert! from 1954 (by the way, I look forward to the day when I’ll put in front of my audio system a dedicated chair such as the Ballerina Sweetspot from Klutz Design, see HERE). Everything was simply spacious, extensive – it can’t be called anything else. For a while I worried if it wasn’t the effect of “pumping-up” the sound as the spell soon breaks and we are left with exaggerated, monotonous sound. But no – the differentiation of the Korean amplifier is sensational on many levels. There is no question of boredom, of being “overburdened” with sound. It is relaxing yet alert; kind of relaxation in readiness…

Despite it sounding like a far-fetched oxymoron, music played on the reviewed amplifier gives a real “kick.” This is due to a few characteristics, rare in themselves and almost unique when combined. I’ve already mentioned one of them – large phantom images. The other two are incredible purity of all frequency sub-ranges and surprising, even when we are already accustomed to the volume, bass. All this has its consequences in general sound shaping as there is nothing for free. But let me take the liberty of saying right now that this is what I’m looking for in the reproduced sound; that’s what “gets me.”
First of all, PURITY. This characteristic is usually described as freedom from coloration or distortion. For me it's something more complex. Lack of distortion and coloration is also characteristic of a device sounding “clinically clean”, i.e. devoid of emotion, internally dead. It is not enough not to add anything (or add as little as possible); what’s equally important is not to take anything away.
Purity of which I speak in the context of this amplifier means a more direct experience, than with other even most “phat” devices, of different sounds, different instruments being real (genuine). It is the kind of purity not resulting from thinning out the sound and emphasizing its attack, because that's just hogwash, but reducing distortion to such level where the advantages of that kind of sound processing fully cover its flaws, mostly a result of an overlap with other problems. Let me repeat – it is a full and deep sound, with powerful, saturated bass and large phantom images; pure, vibrant and accurate, nevertheless.

The bass I'm talking about is an integral part of other frequency sub-bands. If I mention it separately, it’s because it’s perhaps the most surprising element of this sound. Its lower part is not very strong and is rather emphasized by higher harmonics than a real presence. You can hear it especially on tracks where all other instruments build on it, such as the bass in Michael Jackson’s Billie Jean, the rocking on the Depeche Mode maxi-singles, or the powerful drum on Anabasis by Dead Can Dance. No wonder – 15 watts per channel, probably not doubled into 4 ohms, is but a shadow of what the Accuphase A-200 and the Soulution 710, to which the AMP-11R was compared, are capable of. Nevertheless, listening to music with it, also that rich in low sounds like trance music where the climate is built on the low bass foundation, was surprisingly, even refreshingly honest; it was simply a great sound.
It seems that what’s behind is intentional sound shaping. We get sound that is exciting and compelling rather than boring, even when it’s “boredom of correctness.” It is not entirely accurate, even though its clarity is brilliant and its tone and response, apart from the obvious low bass roll off, very balanced. One can hear that something is added in midrange and treble, making the sound very energetic, active. It's just that it happens every time and with all recordings.

After careful audition it’s impossible to think of this presentation as something “well-behaved.” Each sound aspect of the reviewed amplifier ideally matches the surroundings, blends in and does not draw attention. Even though treble, very extensive, rich and active will show more music information than the vast majority of other amplifiers, except perhaps the already mentioned units as well as the best SET tube amps (based on the 2A3 or the 300B). For some time then we will follow everything that's going on, not just because it’s absorbing in itself but because for most listeners it will be, I'm sure, something new, something they have never experienced before. After getting used to the fact that our earlier listening to music was crippled, devoid of treble, we will let go and everything will be restored to balance.
Such accurate, fast and dynamic sound can be easily ruined by not saturating it with something “beyond” detail, something “behind” the sound of basic instruments. The AMP-11R is not an unrealistic amplifier, however, and it doesn’t do some things – it reduces reverb and focuses the sound between the speakers without clearly expanding it beyond. Punch, low bass extension and a sense of absolute fullness of sound are out of question, unlike the aforementioned amplifiers. Nevertheless, it is an absolute surprise and makes listening to music a most joyful experience – not “in spite of” something but “thanks to” that.

AMP-11R + headphones

This is not the first time I deal with a situation where very good, or in some aspects truly spectacular, sonic characteristics of an integrated amplifier carry over into the realm traditionally belonging to headphone amplifiers. Previously it happened with the Leben CS-300 X [Custom Version] amplifier and two amplifiers from Cary Audio, the CAD-300-SEI and the SLI 80. Every now and then, I would also get very good results with other devices, preamplifiers and digital players, but when it comes to absolute top sound such “transfer” has been rare.

All the more surprising was then what I heard after connecting the headphones to the AMP-11R. I could not believe the sound quality with the HiFiMAN HE-300 and the HE-500, but most of all the HE-6, top designs from this manufacturer which so far only suggested their potential. I listened to them paired with dozens of amps and only in a few cases got somewhat of a full response. Still, always limited by something, somehow conditioned. The AMP11R and the HE-6 is a unique combination, without the need to justify anything, without having to extrapolate what I hear and relating it to my previous experience.
Sitting comfortably with our headphones from Mr. Fang Bian on our ears we hear sound that is on the one hand energetic and beautifully ordered, and on the other calm. The combination of these two marks only the best designs. In others their designers usually try to polish one of these elements. Here we have both.
The system, in addition to the above mentioned amplifier and headphones consisting of a the Human Audio Libretto HD CD player and the Klutz Design CanCan headphone stand, which I take to be an integral part of my auditioning system, was almost as perfect, and in some areas even better, than my current reference – the Leben CS-300 X [Custom Version] amplifier paired with the Sennheiser HD- 800headphones. The Leben with the Sennheisers shows more saturated bass and low midrange, the sound is however a little bit more “moist”, not as clean as that derived from a combination of the Korean amp and the American-Chinese headphones. The speed of the magnetostats combined with extremely wide bandwidth and precision of the amplifier’s SATRI circuit resulted in something that goes beyond the usual discussion of “treble,” “bass” and “midrange.” It brings another dimension of sound. I missed something of the calmness of the Leben and the Sennheisers but I had no problem moving from one system to the other. Over time, I noticed I spend more and more time with the HiFiMANs on my ears. And it is only a narrower and more focused in the middle soundstage of the HiFiMANs and the Bakoon that markedly differentiates these two sets, in favor of the Japanese-Austrian system.

Because auditioning the HE-6 made an immediate impression on me, I had much less time left to listen to the other headphones in my collection. However, I’ve done my homework and found some combinations I can recommend with a clear conscience – those I would also be happy to use myself every day.
HiFiMAN HE-500: Very fast sound, powerful, low bass, high transparency. The sound, however, focused in the center of the soundstage and the band around several kHz clearly emphasized. Generally, everything seemed much more compressed than with the HE-6.
HiFiMAN HE-300: A much better synergy than with the HE-500. The sound saturated and full, with slightly contoured edges of the frequency band, but without exaggeration. Powerful, low bass and rich, detailed cymbals. The latter without brightening and even with a slight withdrawal at the edge. Midrange somewhat “paper-like” and not fully saturated but overall a very satisfying combination.
Beyerdynamic DT-770 Pro Limited Edition 32 Ohm: The whole less saturated than with the HE-300 and more distant, not so tangible. Low end, however, smoother and better differentiated, and similarly treble. The latter more open, although not as much as with the HE-6. A slight emphasis on upper midrange gives it freshness and panache. No sharpening or brightening. The combination can be interesting but I’m out.
Beyerdynamic DT-990 Pro (600 Ω): Oh baby! – How great these headphones are doing, despite being about fifteen years old! Their earpad cushions have been replaced a few times, the diaphragm, however, and all other components are original. The most tonally balanced sound throughout. Not as selective and defined as the Sennheiser HD800 and the HiFiMAN HE-6; it can’t stand up to them. But the most balanced nevertheless, simply the coolest. Slightly lacking saturation as a whole, not as direct as the HiFiMANs. Regardless, it can be enjoyed without any fatigue for hours. AKG K70: A surprisingly successful combination. Not the most detailed and differentiated sound but excellent dynamics (yes!) and vibrance. Both top and bottom (extreme edges) rather withdrawn. Treble and upper bass firm and fleshy. Phantom images shown close up, tangible and solid. A real surprise.
AKG K271 Studio: A clear withdrawal of treble, a lack of low bass and a stronger emphasis on midrange attack. Overall, however, the sound is pretty good and balanced. It’s a bit “plastic.” i.e. lacking saturation and tangibility, but on the other hand there are no problems with treble, which many other headphones had. A classic still holds its own.
Sennheiser HD800: The sound that I could put almost on par with the HE-6. This combination didn’t have so good resolution and selectivity as with the planar headphones, but bass seemed to be better accomplished, full-bodied. The tonal balance was set higher than paired with the Leben, with a slight emphasis around several kHz, but without serious consequences. A really great system – I recommend it to anyone!

Conclusion

Journalists reviewing audio products are tired of them, often bored. Everything happens over and over again, in a very similar way (if we are care about listening sessions repeatability), year after year, often for decades. While it may not always be apparent, a sheer repeatability of the process of auditioning, describing the sound and product design, placing that in a broader context, telling manufacturer’s history, introducing the owner or designer, taking and processing the pictures, sooner or later lead to some kind of cynicism – nothing more can surprise us. Even something as unique as – for example – the Siltech cable system I had at home for a few days, costing (trifle!) 200,000 USD! Maintaining a fresh mind is really difficult in this situation. The kind of excitement every beginner feels, the excitement associated with getting to know increasingly better product is somehow gone over time and what remains is a routine each journalist worked out personally.

One of the best ways to rekindle what we do is listening to live music – during concerts, recitals, in the recording studio and on all other occasions. In my case, it means going out two or three times a month. More often during “hotter” periods of time. But it all makes sense only when music, audiophilism and everything associated with it are placed in a broader context. When we have a loving family, eat well, read, drink good alcohol (I will tell you some time a history associated with beer) or have tea, etc. When we simply live a good life. Then we find out that music is more than just organized sounds and audiophilism more than only striving for better sound. We come to realize that it is a way of life, which can be exciting even after many, many years after our first steps in this profession. Provided we meet on our way the right people, right manufacturers and right products.
The amplifier I’ve told you about this time is one of those devices that appeal to all our senses in a consistent, coherent way, reflecting a corresponding idea of its designers. Its sound is exquisite, its design stunning, and we actually get two devices in one: an integrated amplifier and a headphone amplifier. The Bakoon breaks out of the testing routine and is beneficial in a broader sense, not just offering a nice presentation but also bringing a kind of balance to our life. I rarely get similar feelings about the reviewed audio components; when I do it is mostly with Japanese products.

It’s worth, however, turning attention to the context in which the AMP-11R should be found. Be sure to pair it with speakers with even impedance response, preferably rather high and reasonable sensitivity (although the first condition is more important). The Harbeths (perhaps except the smallest model, which sensitivity is quite low) are the obvious choice. Both the M40.1 as well as the M30.1 will sound fantastic, especially the latter, smaller model. Similarly, less expensive speakers like Sonus faber Minima Vintage will make a good choice. Another manufacturer that can be recommended en block is Spendor. Lastly, of course, speakers designed specifically for low power amplifiers, e.g. the J.A.F. Bombard should be a natural target. When it comes to headphones, obviously I haven’t heard everything and I'd be curious to hear the Bakoon paired with top models from Grado and Beyerdynamic. What I do know is that the HE-6, the most expensive HiFiMAN planar headphones are a worthy partner. That’s the first time I heard them sound so well. This pair is for me an equivalent system for the Leben CS-300 X [Custom Version] and Sennheiser HD800. Granted, they are different but it’s the same league. Simply saying, RED Fingerprint!!!

The system receives RED FINGERPRINT award.

Testing methodology

The amplifier was tested in an A / B comparison, with known A and B. In addition to the reference Soulution 710 amplifier and the Ayon Audio Polaris III [Custom Version preamp], I also used the Accuphase A-200 power amplifier and the Leben CS-300 X [Custom Version] integrated amplifier.
The reviewed amplifier was sitting on the RCK-11dedicated stands, and those in turn not on the accompanying set of cones, but the finite elemente Ceraball feet. The whole was placed on the Acoustic Revive RAF-48H anti-vibration platform. For components coupling I used the top Royal Signature Cables Double Crown cables from Siltech - a power cord, a power strip with its own cable, an interconnect and speaker cables. Apart from the reference CD player, I also used the Human Audio Libretto HD battery powered CD player. I made several tests with the Bakoon Products EQA-11R phono preamp connected via the SATRI current input. The turntable used – Dr. Feickert Analogue Blackbird. The amplifier sounds best when it is fully warm – give him an hour to stabilize temperature before sitting down to listen.

DESIGN

The AMP-11R is an integrated amplifier with an outboard power supply. Both units are the same size, and their enclosures are made in exactly the same technique. The enclosure is made of a solid aluminum block with milled out chambers for electronic components. This aluminum block is secured from the bottom by a bolted-on aluminum plate, protruding slightly at the rear of the unit. The protruding section sports orange colored descriptions of inputs and outputs. Incidentally, orange is manufacturer’s color of choice – the very nice logo on the front panel has the same color. The faceplate is small – it’s a tiny unit – and the only visible elements apart from the logo are an orange LED seen through the gap between the main unit body and the bottom plate and a volume knob outline. The knob, if we can call it that, is completely unusual as far as knobs go – a horizontally positioned flat aluminum disc, flush with the rounded unit corner. It sports a slight indentation indicating volume level; however, it would be better to mark it in a more visible way. It might be worth knurling its edge to make turning it easier. However, apart from that minor complain the unit looks simply stunning! There are two basic finish versions, silver and black. But I have also seen a chrome version, maybe custom made on request. The device is powered up and down using a small toggle switch located on the left side, just below the 6.3 mm headphone jack. Signal to this connector is supplied via a pair of resistors straight from speaker terminals. The gain can be set in three steps with a small jumper inside the amplifier.
On the rear panel we have solid, gold-plated Canary speaker connectors (actually, all connectors come from this Japanese manufacturer) and two pairs of inputs – SATRI link on BNC sockets and a conventional voltage input on RCAs. We select between them with another toggle switch.
The external power supply is connected to the amplifier via a short umbilical power cord. The power supply unit looks almost identical to the amplifier, except that there is no volume knob, headphone jack and the power switch. It has, however, an identical orange (amber) LED located in the same place as in the amplifier. It only goes out when we pull out the plug from the mains socket.
The whole audio circuit is mounted on one large PCB with plugged in smaller PCBs accommodating the SATRI circuit (that component is manufactured in Japan). The output stage is based on EXICON 10P25R+1-N20R transistors with visible next to them Linear Technology LT1963A ultra-fast, high-current voltage stabilizers. All are mounted to the enclosure. The circuit sports the best passive components one can imagine – Dale, Mills and Caddock resistors, Sanyo OC-CON capacitors, Wima polypropylene capacitors, an Alps potentiometer and many more top quality, expensive parts. The power supply is built on a large toroid transformer and four sizeable chokes. The filtering system consists of 22 modest sized, high-quality capacitors – 6 in the power supply and 16 on the main PCB right next to the gain transistors.

The amplifier comes with the visually and mechanically matching RCK-11 anti-vibration platforms. They are as charming and just as solid as the amplifier. Each unit has its own platform, which consists of two thick aluminum plates. The upper, smaller plate on which the unit sits is decoupled with a few ceramic balls from the bottom one. Four bolts extending from the bottom plate hold the upper plate in place. Both plates move relative to each other but not enough for the whole platform to come apart. The bottom plate sits on four screwed-on metal cones, which I replaced with the Ceraball feet from finite elemente.
It is possible to join two such platforms, one above the other, to form a rack (e.g. for the two-box AMP-11R). For that we get two very rigid side braces up and down.

Marvelous job – both in terms of mechanical design of the enclosure and the platforms as well as the electronic circuit. Very rarely do I see products so refined in every detail.