Robert Koda K-15-EX Preamplifier Review.


There is probably no boutique ultra high-end audio brand that inspires as much mystique and wonders as Robert Koda. Robert Koch, the owner of this fascinating Japanese manufacturer, is no stranger to Mono & Stereo readers. It's been well over a decade since the brand was launched, and yours truly was initially involved in exclusive interviews, glimpses of the Takumi K-70, the K-10 test, etc.  


The Robert Koda Takumi K15- EX builds on the proven heritage and introduces even more advancements and visuals in line with the Poinçon de Genève cachet.


It is a privilege and a pleasure to once again have the opportunity to dive deeper into the unique musical universe of Robert Koda.

K-15 EX


Unlike many exuberant-priced preamplifiers, the Robert Koda Takumi K-15 EX has a lot more going on underneath its elegant and stylish cabinet than it might seem. The Takumi K-15 EX aesthetic is one of timeless beauty, with just the right amount of luxurious gold trim to make it look classy but not bling.


Yes, this is a purist ultra-high-end preamp. No remote to control volume or switch inputs, and no relays. The Takumi K-15 EX is all about refining the concept and taking the straight-wire-gain concept to the extreme with a minimum of components and also with minimum gain (+8dB).


Koch's innovative and unique arrangement of semiconductors, called ITC, was first used in the Takumi K-10. The K-15 EX takes ITC to the next level, dramatically improved and refined in both design and execution to deliver unparalleled subjective and measured results.

The  ITC - Inverted Transconductance Couplingcircuit provides an excellent interface between the source component and the power amplifier. It delivers tremendous power gain with remarkably low distortion while being extremely immune to the negative effects of power supply noise.

The circuit is elegant, simple, unwavering, and effective over a dynamic range of over one hundred forty-five decibels. It is the ideal preamplifier engine and unmistakably Robert Koda.

The inner workings look, minimalist and purist. It is refined and stripped of anything unnecessary, clearly hinting at Robert Koda's earlier work with top-notch tube preamps with triode-based preamp concepts, pure silver wiring, an almost entirely point-to-point design, and choke-regulated power supply.


But that's where everything familiar and similar ends. Koch has spent his entire life refining his own, propriety circuits, and the result is the sum of more than three decades of theorizing and playing around with various concepts to bring them to life and, more importantly, keep them alive.

Strictly selected components, choke regulation for the power supply, strictly separated and shielded chambers made of different materials, and a full inner copper cage covered with a refined gold anodized premium aluminum cover form a harmonious whole. Imagine an audio-quality highest-grade vault.

The implementation of ITC allows the K-15 to produce both balanced and unbalanced output options without compromise. All technical and sonic characteristics are identical, allowing the best possible choice of connection to the associated power amplifier, not to mention providing a bridge between balanced and unbalanced electronics. Each input signal type is treated as native, meaning no conversions are required before application to the main amplifier block in the K-15.

The K-15 EX looks and sounds like a Robert Koda Takumi product, as you can read in this review. Many have subsequently tried to emulate the design and simplicity of the circuits but failed to reach the originality and sound of Rober Koda. 

​THE Volume control


I can not stress enough how important proper amplification is, and I have been a strong advocate of it for a long time. I understand the purist concept of connecting the source directly to the amplifier, and I have tried it countless times only to be proven wrong. The only time it all worked out was with Lamm M1.2 hybrid monoblocks driven directly from a Trinity Audio phono preamp with integrated multiple gain control. But this kind of combination is not applicable to most people. 


The preamp is a cornerstone of any high-end audio setup, and the role of the preamp is far more important than just a casual interaction and a node that acts as an input and output selector with a few decibels of extra gain. The consonance of system gain begins with the preamplifier.

The gain is the epicenter of any high-end audio system. Not only every album but with modern listening habits, every track requires an exact volume setting to achieve symmetry and unity of gain. Only at optimal playback volume the energy of the music is fully appreciated and presented to its fullest extent. 

In its central role in the final sonic outcome of the K-15 EX, the volume control at the epicenter of the preamplifier is a thing of beauty, extravagance, and depth of quality.


A massive, custom-designed, and built L-pad eight-channel switch/attenuator looks (and feels when turned) like a finely crafted Swiss watch mechanism and uses only one pair of 256 finest nude audio resistors per channel in the signal path with the volume selected. These are very special parts made exclusively for audio. 

The switch itself maintains perfect contact pressure. The contacts are solid silver and generously sized. All aspects of the design are of the highest quality.


A similar approach follows the selection of mechanical inputs specifically designed for the delicate task of processing sub-microcurrent signals and uses no printed circuit boards, relays, or solid-state switches, but manual wiring and mechanical switching of all inputs. The materials and construction have been carefully thought out to transmit the sensitive signals intact over four nines of pure silver wire and 99.99% pure copper and lead-free solder alloy.

The Robert Koda Takumi K-15 EX is all about getting the amplification right, and that's exactly what sets the K-15- EX apart and what it was built for. There is something absolutely valid and well-founded about the way the music is presented, distributed and maintained at every volume turn.


This was clearly audible with dCS Rossini APEX DAC. I found that these two units were made for each other, and especially with the dCS Rossini APEX, set at 6V, there was no audible grain or lack of gain, even on some live recordings where I usually missed a step or two to get the level right.


The lack of a remote control certainly forces one to work differently, which may deter some but not all. Like changing records and enjoying the full side, the Takumi K-15 EX pushes one to adjust the volume of the album, forget about time and space, sit back and enjoy. The other, more drastic way is to place the K-15- EX near a place sedentary with the volume control at the tip of the hand. 

This would, of course, require very elaborate (in length) cable management, which is neither cheap nor easy to do at this high level, but it's not impossible and I've both seen and hands-on experienced such setups. 

The Music


I have lived and owned the original Takumi K-10 for a long time and still think it's one of the best preamps I have encountered in my high-end audio journey. And this is true for both tube and solid-state preamps. 

The K-15 made me listen to the whole album again instead of skipping tracks. This made it a time capsule that took me back to other times when life was less hectic, the world less complicated and people more cheerful, and relationships more fulfilling. 

As always, here are a few tracks that highlight some of the unique aspects of the Takumi K-15 EX preamplifier. 

It's impossible to separate yourself from your cultural baggage, but with the K-15 EX, it's somehow easier, because, despite the different types of music and genres, the center of musical gravitas always remains untouched.


The vast musical meadows and pastures of Omar Avital's "Hafla" from the album New Song were completely free from an aloof gravity that can too quickly go south with too many preamplifiers. 

The Takumi K-15 EX preamplifier warranted the superb tracking of the album's dynamic diversity, with no musical force or energy dominating, and provided a continuous interplay with the core of the music ringing the performers to life and further revealing their wondrous mastery from track to track. 

The K-15 EX was able to communicate the musical expansiveness of the New Song like no other preamp and begot "Hafla" with an unforced and free approach that made for extremely attentive listening, thanks to the higher acoustic density that revealed a newly discovered sonic environment. 

Thus, the listening room could accommodate not only a realistic but also an exceptionally well-filled holographic space, and a potent place ready to kindle emotional triggering of the highest order.

Thanks to the proper handling of on-demand energy, dynamic changes were lightning fast, and micro and macro details leapfrogged several levels up, furnishing head-scratching sensuous interaction and response. 


The plush and enveloping sound of Carl Craig's "Sandstorms" elicit a different kind of emotional connection via Takumi K-15 EX.

The Takumi K-15 EX embodies the nuances of timbre, tone, and color of this intoxicating techno masterpiece and articulates the key points that draw one into music and especially into the world of analog synthesizers, which is a rare quality in a preamp, regardless of price. 

It's rarely written about this type of bond, especially referencing electronic music, but the Takumi K-15 is a clear reminder of being a master of hues, shades, and Technicolor like tonal vibrancy. It's what made the original K-10 such a special and engaging preamp 

Robert Koda's flagship preamplifier exudes a liveliness, track with animation quality and perfect momentum, and spirited exuberance that is radiant and vibrant at its core. 

These particular virtues surely have to do with Koch's earlier work with tube preamps and the logic implemented with ITC circuits and the way harmonicity is evoked and addressed 

The Takumi K-15 EX took the dynamic punch and brute force of the "Sandstorm" with impressive ease, something that many if not most similarly or even higher priced preamps simply cannot do. 

In addition to this, too many preamps act anemic with this Craig composition when it comes to evoking the mood and painting the sonic canvas with infinite minuscule analog virtual realities. Not the Takumi preamp! K-15 EX delivers "Sandstorms" sublimely and vigorously.

But Robert Koda K-15 EX goes even further by emphasizing the sonic impact with the ability to draw full engagement making the listening experience even more intense and zip. 


Sir Roland Hanna's "Mediterranean Seascape" is adorned with so many details, aggregation, and clusters of piano notes that it is extremely hard for any preamp to follow. 

The Takumi K-15 EX skillfully evades the "typical" faux pas of this polyrhythmic dynamism, providing a balanced underpinning that operates beyond sensual sentinels, rendering Hanna's emblematic form from bottom to top without acting reluctantly at any point.

Takumi K-15 beautifully brings out the piano's unique texture, allowing the notes to act side by side so that they both stand-alone and are a constitutive part of the harmonic whole of piano massiveness that is too often taken too lightly as a point of reference. 

It is striking how K-15 EX presents the affinities between the notes and the progressively refined narrative that unites the notes fusing them into harmonic progression in a way that merges and integrates but does not deviate from the narrative and timing.  

The Takumi K-15s depicted the micro and macro cosmos of "Mediterranean Seascape" far more tangibly and effectively than any preamp, furnishing a more detailed and emotionally engaging projection than I would expect. 

On numerous tracks and albums, the Robert Koda Takumi K-15 instantly brought out the best attributes of the music, taking the sonic heights and delights that previously seemed unfathomable to new dimensions.

Regardless of the music, the listener is treated to a unique interactivity that propagates the validity that goes beyond the mere sculptural beauty of the instruments and performers, reflecting reality with superior vividness, clarity, and lucidity.

Conclusion


How often have we heard about simple, but not simpler applications in high-end audio? Especially in the absolute upper class. Nevertheless, when a product, and especially a preamplifier, represents an epitome of audio virtuosity that plunges into the heart of music and keeps the spirit of fundamental principles intact, it is more than worthy of pointing it out. 

It may appear and many say that in the field of high-end audio everything had already been invented. As continuously and pleasantly proven, even without all the technical intrigue, the Takumi K-15 EX is a fascinating rendition of an already-proven concept with newly-found discoveries implemented.  

The K-10 introduced a new type of solid-state preamplifier, taking the methods of tube preamps but using semiconductors. 


With many consequent products, the legacy can be lost in subsequent iterations of the brand. Not so with Takumi K-15!

The second harmonics done right!? Exceptional components!? Pure silver in the concatenation? A touch of audio wizardry!? Yes, the Takumi K-15 is all that and more, but most importantly, it's unlike any other preamp, tube, or semiconductor. It combines the characteristics of both and seamlessly transcends both concepts. 


ITC's innovative role in distributing power, brutal and featherlike dynamics, and despite its seemingly low gain of 8 dB, never hold back energy, nor get in the way of the music. 

The Takumi K-15 has an unparalleled sonic elasticity, ensures a glittering stream of music, and allows a one-of-a-kind immersion in the enchanting music's essence, contrary to the effect of gluing remnants of the music phenomenon, that even more expensive preamplifiers cannot escape. 

The Takumi K-15 EX is not just a slightly modified or tweaked sequel to its predecessor. This bigger sibling comes with added performance shifts and then some. K-15 EX is equally majestic but more sonically impressive than the K-10.

The K-15 EX takes Takumi energy to a whole new level of dynamism, with better timing, and more profound natural transparency, and the sonic scope is filled with genuine music establisment.

To achieve the status of a top-of-the-line preamplifier, such a product needs something of refined simplicity (but not bare simplicity) to convey the grandeur of reality. It is truly amazing how complex music is at its core, and the Takumi K-15 EX speaks to the physicality of music, making it a landmark on the aural frontier.


What mediocre preamps or even some top-of-the-line products priced above the K-15 EX lack is bi-oriented interaction, and the absence of a multi-stage, multilevel simulation model. On the contrary, the Takumi preamplifier offers more than the mapping of instruments, filling the aural space. As it should, it delivers distingiused interaction that is evenly distributed across all music genres.

Even if the prestige would be removed, the fundamental value is still outstanding. And in a preamplifier with such a pedigree, if all the glitz is taken away, the real value, the performance should be there. 


And the Takumi K-15 EX is not just another empty golden cage with no inhabitants or an extremely rare or extinct bird trapped inside the cage. The Takumi K-15's inner bird verve around freely and descants willingly. You can not say that about many products no matter the price. 

The term "masterpiece" is so commonly used in the high-end audio industry, but what makes a masterpiece? The foundation of a masterpiece is its composition and all masterpieces seem to be surrounded by a certain mystique.  

Another inseparable proof of a masterpiece is the ability to withstand the test of time, and Robert Koda's slow but continuous production has begotten a few exceptional products that go even beyond what this Japanese handmade boutique manufacturer has already achieved without altering its pace of everything made slowly and considering every single part used its placement, designated place and nonetheless each turn of the wire. 


As with the extraordinary bespoke pieces of Haute Horlogerie, each K-15 is crafted by an artisan himself in almost the same exclusivity as a waiting list of Rolex and Patek Philipe. 

The Robert Koda Takumi K-15 was designed from the ground up to be engaging, even to the point of being seamlessly in sync with the music. 

Adjusting the volume by hand is a kind of continuation of the ritual of putting on a record on the turntable. Robert Koda Takumi K-15 EX reflects the culture and appreciation of time, taking pride and joy in making things, and Koch follows a tradition in which the path to making a product is as sacred as its completion. And the result of such meticulous work is a guarantee of something extraordinary, which the Takumi K-15 undoubtedly is.

In the world of fast-paced, hectic everyday life and the constant bombardment of the senses with everything instant and digital, the Takumi K-15 represents the exact opposite.  


Just operating the volume knob evokes the familiar tactile feeling and clicks of winding a watch with a manual mechanism. 

I am a fan of these watches and own a few, wearing them daily as premium "beaters". I believe that watches should be worn regardless of prestige and price, that wine and wine and whiskey lovers should enjoy their collections with friends (whether Petrus or Macallan), and that records should be listened to, whether they are highly sought-after first pressings or rare contemporary releases. 


I feel exactly the same about high-end audio gear. They are meant to be used and enjoyed, even if they require a tactile commitment by getting up from the listening position and walking to the preamp.  

Of course, this is not for everyone. Just like some supercar enthusiasts can not stand the manual transmission. In fact, there is a whole generation that cannot drive a car with this "old" technology. 

Still, food buffs like slow food. Some watch purists prefer the manual winding of the watch, and Koch prefers the manual adjustment of the volume and is an advocate of slow music listening.

And he creates such a finely crafted, handmade product that belongs to the absolute top class. 


There are preamps and then there are THE preamps. The Robert Koda K-15 EX belongs in a sphere and level of its own, where science meets art and represents a most unique fusion that transcends technology.  

The Robert Koda Takumi K-15 EX is Robert Koch's chef-d'œuvre and should be on the radar of anyone for whom money is no obstacle to achieving audio nirvana and putting an end to the endless quest for sonic perfection.   

The Takumi K-15 EX represents a mid-way between art and technology that goes beyond the ordinary to not only leave room for the extraordinary but also to create a habitat for emotional force to come through. 

Koch has long left behind the legacy of Audio Note Japan Kondo and his work thereby developing his own meticulously crafted works of art.  


Koch has amassed a vast fund of knowledge and experience throughout his life resulting in a most unique virtue where electronic and mechanical parts fade into the background and the music takes center stage. 

The Takumi K-15 EX represents the Grande Sonnerie of Robert Koda, where the attention to detail does not end on the inside but rounds off the luxurious exterior with soft hand-brushed golden anodized chassis, gold-plated inserts, and a ruby lens.   


The monumental main chassis is made of a solid copper envelope that provides excellent electromagnetic shielding against external influences. By using a layered construction of copper as the chassis and a graded aluminum finish, both esthetic and electroacoustic qualities are met.


My affection for Koch's creation goes way back. It has been ten years since I reviewed the original Takumi K-10 preamplifier, and even longer since I had the pleasure of spreading the word about this unique boutique manufacturer to our readers around the world. 


The Takumi K-10 was a breaking point for Robert Koda and the continuation of a phenomenon fixated with the now discontinued, iconic, equally mystique, and highly unique Takumi K-70 hybrid power amplifier.


K-10 was direct descended (tech-wise) from the Takumi K-70 and a reason that Koch could develop the K-10 and ITC circuit concept.  


While the K-10 has similar things to offer, the Takumi K-15 EX goes even further by bringing out the dynamic lightness and warm nature of the music even more.

Simplicity is the ultimate sophistication. Another overused axiom. Yet... The Takumi K-15 EX nails it, and skirts around it in every respect. 

The Takumi K-15 EX thoroughly encapsulates the sonic virtues that captivate the ear and the mind, not only drawing the listener into the music. It also brings out true artistic achievements to be fully comprehended.   

Robert Koch Hometown

It can take a lifetime to understand and explore the useful applications and directions to create something worth pursuing, be it a theorem or a working concept  

Operating at the vanguard of properly researched and implemented advances is a daunting task that not everyone can take on. Many concepts have been abandoned in favor of a solution that follows the path of desire to create something extraordinary, a sonic maxim, and Takumi K-15 EX completes the embodiment of Koch's creative folly that spans four decades. 


The result is enchanting, to say the least, and it's easy to see how much craftsmanship and attention to detail went into making the Takumi preamp, making it a rare high-end audio heirloom. 

Still!

Robert Koda Takumi K-15 EX preamplifier can not just be inserted into the audio system and expect magic to happen. The Takumi K-15 EX needs the right habitat, and a well-balanced high-end audio system where it can breathe, evolve, and develop its full impact.   


For what it represents musically, and not least for sounding so adhere to the core of the music and delivering a cornucopia of musical delights, I give the Robert Koda Takumi K-15 EX preamplifier the Mono & Stereo 2022 Editors Choice Award.


In a world where almost everything imaginable is up for grabs, it's good to have an antidote, a different kind of passionate audio liaison, that ignites the essence of high-end audio. 

The missing links in my mapping of Robert Koda's celestial sonic entities are the Takumi MC-ONE and the Takumi K-160. When the stars align, I will be happy to report back and share my findings with you. 

Until then, Takumi K-15 EX is a setâr that elicits my deepest appreciation for Robert Koch's work and reunites me with Robert Koda's raison d'être.

I would like to thank Absolute Sounds London and Imacustica Lisbon for arranging the review sample of K-15 EX. 

 •

Matej Isak

Price

  • 70.000 GBP

Technical Specifications

  • Output: SE X 2 pairs. True balanced X 2 pair
  • Input: SE X5 pairs. True balanced X5 pair
  • Gain: Plus 8dB
  • Output impedance: 60 ohm single ended, 2X 30 ohm balanced
  • Input impedance: 50K ohm single ended, 2X 50K ohm balanced
  • Signal to noise:  114dB A weighted at 1V
  • Frequency response: 20Hz to 20KHz +/- 0.03dB
  • Distortion: 0.00003 % @ 1Khz at 2.5V into 100K ohm. Estimated due to measurement limits.
  • Power consumption: Off – 0W On – 30W
  • Weight: 29Kg unpacked
  • Size: 389mm wide, 385mm deep and 158 high excluding feet

Contact


Robert Koda LLC
392-1 Okawa Higashi-Izu 
Shizuoka prefecture 
413-0301
Japan 

Tel/Fax +81 (0)557 23 2882