Having made extensive use of its Square Tube architecture in its amplifiers, French electronics designer and manufacturer Kora is now applying this technology to its DAC140. This hybrid configuration combines tubes and transistors to deliver exceptional musicality.
Smooth and precise, the Square Tube’s music reproduces all the details and subtleties of the sound message with remarkable accuracy. With no amplitude limits, signal dynamics are natural. The sound reproduction is beautifully spatialized. The sound image becomes three-dimensional. The Square Tube configuration, designed by Kora and exclusive to it, differs fundamentally from hybrid architectures. Here, the tubes are no longer used as simple preamplification stages, but are combined in a arrangement comparable to that of an operational amplifier. The Square Tube architecture uses two ECC 82 and two ECC 83, double triodes that are well known to fans of ‘tube sound’. Four triodes are used to filter the analogue signal. To ensure that these tubes work in optimum conditions, Kora has taken care to stabilise their supply voltages, +240 V and -240 V, a solution that guarantees a particularly low noise level usually reserved for the highest quality components. The signal delivered by these fully analog stages is of exemplary stability and homogeneity. This configuration offers not only the possibility of achieving maximum dynamic range as-bandwidth, but also to preserve the balance and coherence of the musical message.
However, in order to exploit the full reproduction resolution promised by the Square Tube configuration, it requires a high-performance digital-to-analog converter capable of delivering the analog signal with a very high signal-to-noise ratio.The most effective way of achieving this is to oversample the digital stream. Kora has decided to make the DAC140 work on 32 bit/768 kHz streams. This choice also simplifies the design of the anti-aliasing filter while reducing the noise in the frequency band to be processed. To this conversion operation, Kora has chosen an AKM up-sampler combined with a Rohm converter. This combination, dedicated to digital signal processing offers the possibility of capturing the slightest information in the music. The AKM up-sampler increases the sampling rate to 768 kHz. This operation eliminates the artefacts associated with to digital conversion in the audible frequency range. The Rohm DAC, on the other hand, supports conversion synchronised with the original signal. Finally, output filtering is entirely analogue, output filtering is entirely analogue and is carried out by the Square Tube stages.
The DAC140’s sonic signature is thus fully revealed in a variety of ways, the different characteristics that determine its temperament. The first is the notion of dynamics, pushed as far as possible for a digital-to-analogue converter. The music is alive. It has a dynamic range and scope that bring a new dimension to listening. Added to this is the DAC140’s ability to restore a signal of exemplary finesse, bringing out a host of micro-information and nuances. The DAC140 also stands out for its sound image which, here too, takes on a whole new dimension. The soundstage develops with remarkable breadth in all three dimensions. The musical space is airy and layered. Each of its components is exceptionally stable. Instruments and voices alike are natural and realistic. Finally, the signature provided by the use of tubes gives the listening experience a great deal of substance and for an uncommonly pleasurable listening experience.
In order to fit in easily with the highest-quality configurations, the DAC140 is equipped with high-quality connectors giving access to all types of in connection. The most frequently used standards. For digital inputs, the new Kora converter is ready to go. Four inputs on RCA sockets. Two Toslink sockets are for optical connections. A USB-B port is also provided so that the DAC140 can use digital streams from a computer in optimum conditions. Finally, two XLR sockets in AES/EBU format are located on the rear panel to enable the digital streams from the highest quality equipment.
As for analogue outputs, the essentials are present. Two RCA sockets are dedicated to connection of the DAC140 to any conventional preamplifier working in unbalanced mode, while here again, two XLR sockets will allow you to use a symmetrical link, a configuration that is always preferable for optimise the signal-to-noise ratio of the link and avoid the slightest detail of the reproduction.
INSTALLATION
We received a brand new DAC140 which we quickly connected to our various digital sources (CD transport and network transport). As it was, the performance was already particularly convincing. But after a few dozen hours of use, the sonic sensation became remarkably smooth. We would therefore strongly advise you to run the system in for a few dozen hours. And don’t hesitate to read the manufacturer’s prose carefully, as they’ve done a very good job in this area. Generally speaking, we rarely read instruction manuals, but Kora can be cited as an example for the quality of its two user manuals.
SOUND
Before starting to write this section, we drew up a list of qualifiers and sensations. All without exception related to the notion of the ‘naturalness’ of the restitution. The more we listened, the more we were struck by the fact that the DAC repetitive nature of the DAC140, which brings a very specific light, being able to perfectly the characteristics of each recording. This gives rise to a very wide range of sonic properties and gives the listener the opportunity to benefit from a wide-open window on each and every disc. Whether on a file or an iridescent disc, the DAC140 perfectly decrypts the message, making it incredibly readable and, above all totally free from harshness. As we all know, when the resolution, the message becomes considerably smoother. This is the example. Not only does the DAC140 demonstrate a wonderful musical coherence, but does so with a very pleasant sense of with a very pleasant feeling of completeness.
When you listen, everything is there, perfectly in its place, nothing disturbs the natural, logical order of the éléments that combine to reproduce the message as a whole. It’s really obvious on the extension and extinction of the notes. With the DAC140, it’s a real pleasure to listen a varied flow of sound, never tiring or repetitive. The sound is beautifully aired, fills the stereophonic triangle, creating a spacious an ample sound bubble in space. Of course, our hi-fi culture suggests that this proprietary tube arrangement is sovereign in the way it puts sound into perspective. But it also brings many qualities to the tonal balance. The DAC140 delivers soft, luminous and slightly woody timbres that delicately caress the ear. One of the most revealing indicators is that during a listening session with the DAC140 musical tracks can be enjoyed in their entirety. Never a sectarian, this DAC works with everything. We alternated between a large a wide range of musical styles, and even radically different musical styles, without ever from one to another. This is also because that this converter has a great way of managing energy, capable of truly demonstrative punch and impacts when required.
OUR CONCLUSION
Looking at the DAC140 from every angle, we can only praise its build quality and, above all, the pertinence of its technical choices, which totally refute the ease of venturing into proprietary solutions. Listening to it, you get a perfect sense of what the designer wanted to emphasize: a sharp eye for the essential. In other words, the quality of the modulation of the musical phrase in all circumstances, whatever the amount of detail it contains. The DAC140 gets to the heart of the matter, without ever forgetting the accessory, which it places as accurately as possible. This is a machine that demonstrates maturity and superb musical cohesion. It is so coherent that it can do justice to any type of system, so great is its coherence. For our part, we were totally won over by its ability to reproduce any type of music with equal elegance, and, above all, an authenticity that is rare to find to this degree of success. So, to conclude of course, €9,000 is a sum that many people won’t be able spend on a DAC. But for all that, not for a moment do we doubt the relevance of our choice of our choice in awarding it our Remarkable label. The DAC140 is one of the most musical converters on the market at any price.
