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Digital cable


KBL Sound

Manufacturer: KBL Sound
Price: 3950 PLN/1 m

tel.: 696 551 492


he Digital Revolution 2.0 that has been happening in audio world in recent years changed the whole industry. It shifted the focus to devices that play and convert digital signals. Suddenly digital players, USB converters and DACs became very important parts of many manufacturers' activities. While it is an USB cable that is used between computer and DAC, most other digital connections are made with coaxial S/PDIF cables.

There are not so many Polish digital cables. To make them one has to combine listening experiments with a technical rigor that will allow cables to match industrial, measurable standards, among which the most important one is impedance of 75 Ω. To fulfill such requirements one needs something more than just a small workshop, it requires knowledge and access to proper manufacturers that actually make such cables. As I'd mentioned in my review of KBL Sound Red Eye power cable: manufacturing audio cable is a complex job that only few companies around the world undertake. Usually these are large companies manufacturing OEM cables for a large number of small finished cables manufacturers. Having a digital cable in a portfolio in the top Red Eye line is a sort of nobilitation for KBL but on the other hand also an obligation.

The RCA-RCA (S/PDIF) termination is the only one available in : 1 m, 1,5 m and 2 m lengths. It sports a characteristic red-black sleeve and nicely looking connectors made of tellurium copper with carbon fiber jackets. It is delivered in a nice box giving a very positive first impression of a product of a professional manufacturer.

KBL SOUND in „High Fidelity”

KBL Sound

Since that's a digital cable its impedance of 75 Ω was one of key parameters we had to remember when building it. Surely other factors like purity of a conductor mattered too. We decided to use OCC silver that was also artificially aged. Silver crystals are particularly long which makes the whole conductor's environment very homogeneous. Due to this process the sound is smoother and any harshness often introduced by silver is eliminated. Surely we couldn't have any of it to achieve a neutral, well balanced sound. There is a double silver shielding to eliminate any distortion that could effect the sound. We also paid a particular attention to the problem of vibration damping, We used two auxiliary solutions, both based on advanced plastic production technologies (derivatives of Teflon), with the key focus on the internal structure of the cable. Connectors are made of tellurium copper, silver and rhodium plated, with a carbon fiber jackets that offers the best conductivity, best contact and best protection from RFI and EMI interference. They were carefully selected during trials with several different types and are manufactured for us upon our order. We managed to keep cable quite flexible despite the complex internal design.

I think it's a good idea to offer some explanation here, in particular concerning two things. One of them concerns my reference system. When reviewing new Acoustic Revive cables I was truly impressed with Mr Ishiguro's new achievement (see HERE). I declared it clearly more then once. But despite that some people asked me why I hadn't like these cables, which was their conclusion they'd drawn from a few critical words I'd used in my review.

There is surely some misunderstanding here. What I do is reviewing audio products not just praising them. I am not interested in comparing a review item to other products from its price range, nor to less expensive ones (I might do it as a small part of the comparison but conclusions are not the ultimate ones). Doing it this way one could write a review praising particular product but this sort of review wouldn't hold much value. If one wants to find out something of value about amplifier, speakers or cable one has to compare it to much more expensive reference product. Only such a comparison will clearly show the weaknesses of the reviewed product. And only knowing it's downsides one could try to understand what exactly this particular product is, where it fits and where it doesn't, how to use it to benefit from particular set of features – long story short: whether it is a right product for one's needs.

Writing panegyric that say: it is the best product in the world, known universe and beyond is simply stupid. It could boost manufacturers' and distributors' ego, in a short term also increase sales. But a lie has no legs. One doesn't have to be an expert on audio magazines to notice a certain regularity: most reviews are very enthusiastic (about how great the product is), few are very critical. The latter, trust me on that, are in fact agreed with manufacturers and/or distributors, they don't just happen. And nothing new comes from those reviews, readers don't really learn anything new about the product. I think it is one of the reasons why many audiophiles don't trust reviews in audio magazines.

A second “thing” concerns Acrolink cables. One of my reference cables is RCA-RCA digital Mexcel 7N-DA6100. I listened to only two other cables that offered better performance but both were way more expensive. Acrolink offers everything I need: fidelity, stable performance over time and it works with any device. And now: I heard more than once that it was a cable delivering “lean sound”. With all due respect: that is not true. It delivers very precise, detailed sound but also with proper “weight”, richness. What for example Siltech Double Crown offered was even better density, richness of the sound. But it doesn't mean that Acrolink's midrange isn't rich enough, or that it doesn't deliver proper bass. Most cables compared to it sound like they were “hollow” even if the first impression tells us they sound “darker”, more mature. But what we really get is usually some modification of tonality, timbre, some softening of the attack phase and decreased resolution.

To the point: Red Eye cable, as you are about to find out, is a great product. That made this test a great pleasure. But it also brought some responsibility on me. I spent more time testing it then I usually do. I compared it to above mentioned Acrolink Mexcel 7N-DA6100 (as top reference), and with Acoustic Revive COX-1.5tripleC-FM (copper; as low point reference) and Oyaide DB-510 (silver).
The source of signal was Philips CD Pro2 transport inside my Ancient Audio Lektor AIR V-edition. The alternative source used for Red Book signal as well as for hi-res DXD one was AURALiC Aries. Signal was then converted by AURALiC Vega DAC.

Recordings used during test (a selection)

  • Miralula. Medieval Music for Saint Nicholas, wyk. Ensemble Peregrina, Agnieszka Budzińska-Bennet, Tacet 213, CD (2014).
  • Zapach psiej sierści, soundtrack, muz. Włodzimierz Nahorny, GAD Records GAD CD 019, „Limited Edition 500 Copies”, CD (2014).
  • Al Di Meola, Flesh on Flesh, Telarc, 24/96, źródło: HDTracks, FLAC.
  • Billie Holiday, Billie Holiday, Clef/UMG Recordings UCCV-9470, „David Stone Martin 10 inch Collector’s Selection”, CD (1954/2013).
  • Cream, Disraeli Gears, Polydor/Universal Music LLC UICY-40023, Platinum SHM-CD (1967/2013).
  • Dead Can Dance, Anastasis, [PIAS] Entertainment Group, PIASR311CDX, "Special Edition Hardbound Box Set", CD+USB drive 24/44,1 WAV (2012);
  • Depeche Mode, Ultra, Mute/Sony Music Labels, Blu-spec CD2, (2007/2014).
  • Fleetwood Mac, Rumours, Rhino, FLAC 24/96.
  • Jerzy Milian Trio, Bazaar, Polskie Nagrania “Muza”/GAD Records GAD CD 017, „Polish Jazz vol 17”, CD (1069/2014).
  • Kankawa, Organist, T-TOC Records, UMVD-0001-0004, "Ultimate Master Vinyl", 4 x 45 rpm 180 g LP + CD-RIIα + 24/192 WAV;
  • Leonard Cohen, Popular Problems, Sony Music Labels SICP-4329, CD (2014).
  • Mikołaj Bugajak, Strange Sounds and Inconceivable Deeds, Nowe Nagrania 001, 45 rpm LP+CD+WAV 24/44,1;
  • Robert Kanaan, Continuum, Soliton SL 383-2, CD + pliki WAV 24/44,1 (2014).
Japanese issues available at

Sending signal via any connection changes this signal. That's an axiom from a philosophical and practical point of view. Digital cables are no exception. The fact that the character of send signal differs from the analogue one doesn't change a thing; what changes are the ways the signal is changed which ultimately translates to how they change the sound.
In my experience digital cables, treated by many audiophiles with similar, low esteem as power cables, seem, at least at first, to introduce smaller changes to the sound than analogue cables, interconnects and speaker cables. But after couple of hundred trials I tend to believe now that the above sentence is true and not true at the same time. It is true as some element responsible for the sound impression don't change. Not so true as there is something changing that lays deeper in the sound, something that gives the sound a proper structure.

Red Eye sounds (I will used this word even though it is rather about the changes it introduces to the sound) in a warm way, delivering large scale sound. It would be difficult to mistake its sound with any other I used for reference in this test. In general its tonality reminded me the one of Harmonix HS-102.
What is even more important is that accent is shifted towards lower midrange which effects the way instruments are presented. This Polish cable presents them bit closer to the listener, which creates also an impression of them being bigger. This cable offers “large scale” sound – something that many systems, no matter their price, lack. KBL cable will introduce large scale, rich sound to any system. They will deliver beautiful, mature sound which a nicely detailed, close foreground, large soundstage and a hefty bass.

Acrolink 7N-DA6100 delivers extremely precise sound. It is fully capable of delivering precise attack and everything that follows. Sound definition is exemplary and so it its resolution. These are surely required features but in practice one won't always be comfortable with them. An example – the latest Leonard Cohen's album Popular Problems. There are two main planes here – Cohen's voice is one and all the rest (instruments, chorus) is the other. These two were recorded in a completely different way, in a completely different acoustic environment and the quality of these recordings differs significantly. Cohen's voice is recorded poorly. Since the artist barely speaks he sand directly to the microphone, and the sound engineer did his best to make everything, even smallest details audible. To do that he used quite heavy compression which translated into quite a rough sound.

In this particular case Red Eye did kind of remastering smoothing out harsh edges, emphasizing lowest part of vocal and rolling off its upper part. I observed a similar effect when listening to 1952 Billie Holiday album. The vocalist's voice seemed large, warm, and the accompanying trumpet seemed a bit withdrawn. It seems that this is a characteristic feature of this cable as I observed similar effect on all recordings I listened to. With some of them it gave the music a new, better quality improving some unwanted “effects”. But with others, like for example with Jerzy Milian's Bazaarem, or Robert Kanaan's electronic music of Continuum, it changed the overall character of the presentation making it warmer, darker, and loosing a bit of their clarity that was delivered by Acrolink, Acoustic Revive and Oyaide.

To be honest – I don't think anybody could really dislike this sound. I mean there it might lack some precision so don't expect equally perfect imaging as Acrolink or the top Siltech deliver, but there will be amazing richness and depth to the sound. It doesn't mean that Red Eye offered dark sound lacking clarity or a spark at the top. This could be true if it was a case of an analogue cable. When it comes to digital cables changes are about something deeper “under the skin” rather then just only on the surface so one has to think about them differently. Changes a digital cable introduces to the sound are not of “wow!” kind, but rather they make listener more interested in the music, make one wonder what will come next with another piece of favorite music.

Especially because the sound offered by this cable is very well aligned, very coherent with top treble being a bit of exception as it seems to be slightly emphasized (because upper midrange seems slightly rolled off). One will notice that only when listening to puristic classical music recordings and even then it should not be a real issue. The attention will be focused on lower parts of the range, on richness and palpability of the sound. It is one of very few cables that really benefits form offering exceptionally palpable sound. Any recordings listened with KBL will sound nicely and will offer a lot of satisfaction to the listener.


It is very difficult to combine precision and density on the highest performance level. I encountered that maybe twice in my life, one being listening session with the top Siltech cable. The most expensive Acrolink follows the path of precision and dynamics without losing proper richness of the sound. The bass extension is better then offered by any other cable I know and the same goes for precision of imaging. Red Eye can do equally well. But it delivers something that is the main difference between Acrolink and Siltech, density, richness of the sound, at the expense (there is always a cost of doing something better than others) of attack and resolution. It always allows for amazingly pleasant contact with music and it never does anything wrong. It will save more then one expensive system that delivers a lot of sounds and but not music. When used in the most expensive, most sophisticated systems their owners will have to find their own answers whether Red Eye introduces changes they require. But even there, among top systems, KBL will often find its place being the final puzzle making the system a whole and allowing its user to truly enjoy any music.

Most information about the design of Red Eye Mr Robert Szczerbowski already gave you above. Let's summarize: it is an unbalanced cable (available only in RCA-RCA version) with aged, long crystal OCC silver conductors. It sports a double shielding, also made of silver. Dielectrics, derivatives of Teflon, serve also as damping material. Clamped connectors are made of Rhodium plated Tellurium copper. Connector's body is made of carbon fiber. Cable is quite flexible which make implementing it in a system very easy. It is delivered in a very nice box.

This is as good place as any to announce that KBL Sound Reference Power Distributor and KBL Sound Red Eye power cables became parts of SYSTEM B, together with Graham Audio LS5/9 speakers, Leben CS-300 XS (Custom Edition) amplifier, Siltech Classic Series signal cables, Pro-Ject Xpression1 turntable and Linear Audio Research LPS-1 phonostage. This system is used mainly for „Music To The People” magazine but also for my reviews conducted for „High Fidelity”.


Soliton SL 383-2, CD (2014)

When it comes to art everything is connected with everything. Even these artists that choose their own, solitary path, can do that by refusing to be a part of some larger movement. They base their artistic creation on something they touched, inhaled, something that got stuck to them, or just barely touched them. Every artist is a sum of all impressions processed by his own personal sensitivity.

Similar mechanism works also for those who perceive the art. So it is quite natural that once we get interested in some subject, in something that attracts our attention, delighted by something sooner or later we try to explore the subject, to learn as much as possible about it. So in a way a review of the newest album by Robert Kanaan, called Continuum simply had to come after the review (in September's issue of HighFidelity) of the Hołd by Robert Kanaan & Krzysztof Duda & Przemysław Rudzia (see HERE).

Robert Kanaan's album Continuum was released on August 22nd 2014. Robert Kanaan is a composer born in Wrocław, and presently living in Gdańsk. He is known most of all of music he composes for theatrical spectacles. On Bandcamp he describes his music as a: modern „World/Ethno/Electronica”.

Continuum is a concept-album, same as the previous release Gaja. As you can read on artist's webpage this album depicts a vision of a paradise lost, an utopia „Sacred island”, where man live in harmony with “Nature” and “Universe”. Robert Kanaan composed music, lyrics were written by Anna Kobiela – Kanaan (info from her www site: „founder and president of Foundation Re: Akcji Artystycznych FREA-art, director, educator, business coach, mother”), and vocals were done by Katarzyna Chudzik (student of Music Academy in Gdańsk, a participant of TVP 2's show „Bitwa na Głosy”). The recording was done in Kombinat Produkcji Dźwięków, and it was realized by Mirosław Worobiej. The album was issued as digipak. There were two paintings used on front and back cover. The former is Henri Rousseau's (1844-1910) The dream (1910), and the latter is The snake charmer (1907). The Dream was the last painting Rousseau ever did.

I asked Mr Robert directly some questions and that's what he told me:

Wojciech Pacuła: Could you describe the process of making material for this album?
Robert Kanaan: I work on a computer with Cubase 5 software that is a “heart” of this system. As for the sound – apart from a significant VST collection (East West Quantum Leap among others – a full range of instruments on a disc, KONTAKT Komplete, Sonic Couture) I use also sound of some electronic instruments like: Roland XV 5080, Kurzweil K2000, or Korg R3 with vocoder .
I record material as MIDI tracks, trying to play mostly live, using sampling frequency of 96 000 kHz and 24 bit resolution. Simply, instruments sound best when I use these parameters. This material is later pre-mixed.
When the computer can't deal with all the tracks simultaneously I can “freeze” some of them while still being able to use EQ, effect edition and automatics in Cubase. In this way I arrive at my premix, and then I give it, or myself some time before I come back to it and change the project.
When I'm at the stage when premix becomes acceptable, I have to export all tracks to wave files, usually transferring both the effect tracks and my raw solo tracks with the latter at the front and the former in the back (East West Quantum Leap Symphonic Orchestra offers this feature because the material was recorded with microphone in three positions). 

And then?
When this huge folder is ready (it happened that I transferred 38 mostly stereophonic tracks in Continuum so folder was HUGE), I finally take it to the studio. I have been working mostly with Mirosław Worobiej from Bydgoszcz for some time now. Previously he worked as sound engineer in Radio PiK, but now he works in his own studio called KOMBINAT PRODUKCJI DŹWIĘKU. Sometimes I work with other sound engineers too in different environment like in Radio Gdańsk for example. I believe that an objective sound engineer can spot the key elements of particular piece of music and competently expose them which makes recording clearer, apparently simpler. That's what I want.... What is really achieved, that's not for me to judge. For the last album also Katarzyna Chudzik's vocals were recorded in KOMBINAT PRODUKCJI DŹWIĘKU studio.
As for studio's equipment - Continuum was made using the newest version of PRO TOOLS, with a set of very good effects, both internal and hardware ones like: TC Electronic, Alesis, Brainworx Studios series, obviously WAVES top series and others. Usually we work together with sound engineer mostly using classic Yamaha monitors, sometimes switching from near to far field listening. More information about studio can be found HERE .

Finally when the material is almost ready, mixed it comes to listening sessions – I personally use my Beyerdynamic DT 990 PRO cans – and later it goes to mastering. At this stage mastering engineer works on wave files and uses such devices as TC Vitalizer, plus he runs music via tube devices. Finally he uses WAVES MAXIMIZER, but only to make changes of 2-3 dB. I don't want my music to sound “flat”. It is not an easy process, you need to find the golden mean.

Material for Continuum was mixed using 24-bit depth and 48 000 kHz bitrate. Most studio hardware use this standard. So still in the same resolution the material is mastered and only when it comes to finalizing master “tape” it is down-sampled to a Red Book CD standard.

Any other interests than electronic music?
Apart from electronic music I've been focusing my activity for some time now on string quartets. First time was when I was commissioned by City of Żnin to compose a music poem that was titled CARMINA IANICII. To perform it I invited LA SCALA quartet form Gdańsk, singer Iza Plath from Baltic Opera and actor Andrzej Pieczyński. One of the things I do presently is a transcript for string quartet of my music for Bal u Salomona play. In fact I did a lot of illustrative music, mostly for theatrical plays, in the past. On many occasions I invited different soloists to perform my music – violist (Marta Wiśniewska), soprano (Elżbieta Stengert), sometimes I also experimented recording actors' voices.
I've been also orchestrating carols for the last few years for periodical charity event "FALA DOBRA" for Pozytywne Inicjatywy Fundation. I mentioned that because this years I decided to base my orchestrations on vocal recordings that were “tuned” and sampled by me. As a main tool I decided to use KONTAKT Native Instruments, although for some effects I used also a free plug-in, Shortcirquit, mostly because it is one of very few that allow working on 24-bit samples.


The sound of Mr Robert's album is well balanced. It is clear that the goal was to achieve sound with impressive, very clear spacial effects. Sound is vivid, agile but producer didn't “forget” about lower end. Sound might seem a bit “light” but that is just an impression. Lowest bass isn't as rich as on some other recordings like, for example, of Novika, Michał Bugajak and other bands performing dance an electronic music. I wouldn't say that there is too little bass here, it is rather a sonic character of this recording.

It seems that what musicians and sound engineer had in mind was first of all clarity and selectivity, also spacing seemed important to them and they achieved exactly what they wanted. Due to proper usage of reverb and spacial effects sound that we get has many layers with sounds from the background smoothly entwining with these placed in the front. It's a really good, solid production.

What's not there? I can't tell you why but Polish productions don't have same large scale of sound as the best recordings done abroad. Even really poorly recorded Mike Oldfield's Man On The Rock album offers richer, more meaty sound. Continuum offers much, much higher sound quality, as it's clearer, with less compression, more spacious. But still this one particular aspect makes Oldfield's recording sound „fuller”. Not to mention old Vangelis recordings, like Spiral from 1977, like old recordings of Jean Michel Jarre from before 1969, that you can find on Rarities from Essentials & Rarities album, and like many others. Surely some credit has to go to newer, more advanced digital instruments, but the other factors are changes in a way material I recorded, mixed and mastered./p>

This is the only one thing I would change about the sound of this album. It's a really cool, enjoyable, easy to listen album. It offers pure and selective sound, no brightness, no harshness or whatsoever. Sound is rather on a soft side so don't need to worry about any sharpness. I would appreciate bit more density of the more, more distinct imaging and larger scale of the sound, but very few recordings are done this way nowadays.

Mr Robert was kind enough to send me, together with CD, also two CD-Rs with the same material but in 24 bit/44,1 kHz resolution, which allowed me to compare Hi-Res files with a final product - a CD that is sold to customers. Differences between Red Book resolution and Hi-Res are always clear especially if you listen 16-bit right after 24-bit material. This case is no different, especially bass definition was clearly better when I played Hi-Res files, but also sound clarity on both frequency range extremes. These differences didn't really influence my take on sound quality of this recording and in fact they were less significant then I'd expected. Than means that change from 24 to 16-bit was done properly.

Sound quality: 7-8/10


- Turntable: AVID HIFI Acutus SP [Custom Version]
- Cartridges: Miyajima Laboratory KANSUI, review HERE | Miyajima Laboratory SHILABE, review HERE | Miyajima Laboratory ZERO (mono) | Denon DL-103SA, review HERE
- Phono stage: RCM Audio Sensor Prelude IC, review HERE

- Compact Disc Player: Ancient Audio AIR V-edition, review HERE
- Multiformat Player: Cambridge Audio Azur 752BD
- Line Preamplifier: Polaris III [Custom Version] + AC Regenerator, regular version review (in Polish) HERE
- Power amplifier: Soulution 710
- Integrated Amplifier: Leben CS300XS Custom Version, review HERE

- Stand mount Loudspeakers: Harbeth M40.1 Domestic, review HERE
- Stands for Harbeths: Acoustic Revive Custom Series Loudspeaker Stands
- Real-Sound Processor: SPEC RSP-101/GL
- Integrated Amplifier/Headphone amplifier: Leben CS300XS Custom Version, review HERE
- Headphones: HIFIMAN HE-6, review HERE | HIFIMAN HE-500, review HERE | HIFIMAN HE-300, review HERE | Sennheiser HD800 | AKG K701, review (in Polish) HERE | Ultrasone PROLine 2500, Beyerdynamic DT-990 Pro, version 600 - reviews (in Polish): HERE, HERE, HERE
- Headphone Stands: Klutz Design CanCans (x 3), review (in Polish) HERE
- Headphone Cables: Entreq Konstantin 2010/Sennheiser HD800/HIFIMAN HE-500, review HERE

- Portable Player: HIFIMAN HM-801
- USB Cables: Acoustic Revive USB-1.0SP (1 m) | Acoustic Revive USB-5.0PL (5 m), review HERE
- LAN Cables: Acoustic Revive LAN-1.0 PA (kable ) | RLI-1 (filtry), review HERE
- Router: Liksys WAG320N
- NAS: Synology DS410j/8 TB
System I
- Interconnects: Acrolink Mexcel 7N-DA6300, review HERE | preamplifier-power amplifier: Acrolink 8N-A2080III Evo, review HERE
- Loudspeaker Cables: Tara Labs Omega Onyx, review (in Polish) HERE
System II
- Interconnects: Acoustic Revive RCA-1.0PA | XLR-1.0PA II
- Loudspeaker Cables: Acoustic Revive SPC-PA

System I
- Power Cables: Acrolink Mexcel 7N-PC9300, all system, review HERE
- Power Distributor: Acoustic Revive RTP-4eu Ultimate, review HERE
- Power Line: fuse – power cable Oyaide Tunami Nigo (6m) – wall sockets 3 x Furutech FT-SWS (R)
System II
- Power Cables: Harmonix X-DC350M2R Improved-Version, review (in Polish) HERE | Oyaide GPX-R (x 4 ), review HERE
- Power Distributor: Oyaide MTS-4e, review HERE
- Stolik: SolidBase IV Custom, read HERE/all system
- Anti-vibration Platforms: Acoustic Revive RAF-48H, review HERE/digital sources | Pro Audio Bono [Custom Version]/headphone amplifier/integrated amplifier, review HERE | Acoustic Revive RST-38H/loudspeakers under review/stands for loudspeakers under review
- Anti-vibration Feets: Franc Audio Accessories Ceramic Disc/ CD Player/Ayon Polaris II Power Supply /products under review, review HERE | Finite Elemente CeraPuc/ products under review, review HERE | Audio Replas OPT-30HG-SC/PL HR Quartz, review HERE
- Anti-vibration accsories: Audio Replas CNS-7000SZ/power cable, review HERE
- Quartz Isolators: Acoustic Revive RIQ-5010/CP-4

- FM Radio: Tivoli Audio Model One