Perhaps one of the most underrated cables in audio, the good ol’ 75 Ohm coaxial digital interconnect is beset on the one hand by those who think it a ‘legacy’ connection, and on the other by those who dismiss any implication that better audio performance can be had by a product that simply passes a digital datastream. It’s all ones and noughts after all, isn’t it?
Clearer Audio makes a strong case for the defence in both cases. In terms of ‘legacy’, while the need to hook a CD player to a DAC is beginning to become a touch out of date, the seemingly unstoppable rise (and ever increasing specifications) of the media player mean it’s not time to count coaxial out just yet. Meanwhile, the ‘bits is bits’ argument is harder to overcome; it should evaporate in the listening test stage when comparing the Silver-Line Optimus Reference 75 digital interconnect to other cables, but there’s nothing quite so robustly affixed as a strongly defended position in audio. Limpets and barnacles could learn a thing or two from some of the more rigid exponents of the ‘it all sounds the same’ club.
Clearer Audio’s nomenclature in general can be a little ‘word salad’ in approach, and the Silver-Line Optimus Reference 75 digital interconnect is no exception. Suffice it to say with that many words in the title, it damn well better be the top of the tree, and it is. This is the ne plus ultra, the flagship of Clearer Audio’s digital range of cables, and is presently only available in 75 Ohms RCA connection. A few years ago, that would have ended up creating something of a non-sequitur, because no matter how true to 75 Ohms you got in the cable construction itself, RCA terminations were notoriously unable to hit any kind of consistent, plug-to-plug impedance. This was why the digital cognoscenti all nodded toward BNCs, because those locking connectors from the broadcast industry were designed to have a consistent 75 Ohm impedance under the widest circumstances. Fortunately, terminations like the WBT 0152 Ag Pure Silver nextgen RCA plug have resolved any inconsistencies in the plug itself, thanks to their platinum-plated, pure silver contacts, advanced dielectric in the plug, and the screw-down clamping system. It’s not the only impedance-constant game in town, but one of the few that isn’t custom made for specific cable designs, and that means a pair of connectors that might cost as much as this whole 1.5m interconnect.
The cable itself is a coaxial design, featuring a central 6N (99.9999%) OCC silver central conductor, and micron-thick silver-plating over a 6N PC-OCC copper in two of the conducting braids (for the return path and the shield). The conductors are insulated by a foamed polyethylene dielectric, the diameter of which is crucial in order to make the cable precisely achieve a 75 Ohm impedance.There is an additional dual-layer active copper foil shield, and a passive silver-plated Nylon braid shield, which is said to provide ‘plane wave shielding’. Clearer Audio’s signature blue-wrapped ‘Super Suppressor’ ferrite rings are affixed at both ends of the cable, it is extensively treated through the build-up process with CAIG Labs treatment, and the fully built cable is then given a 57-hour run-in on an Audiodharma Pro 2.5 Cable Cooker. Despite this, Clearer Audio recommends an additional 50-100 hours to let a cable ‘bed in’ after connection. This level of detail is why the Silver-Line Optimus Reference 75 is not available ‘ex-stock’ but is made to order.
I hooked the cable between the excellent Hegel Mohican CD player (used as a transport) and the outstanding APL DSD-S digital converter. This combination works well, the Hegel introducing just the right amounts of ‘zing’ to energise the APL’s overall presentation, but not so much as to detract from the natural tonal balance of the converter. This combination is, however, somewhat poised on a digital knife-edge sonically, and a perfect indicator of when everything works in harmony, and when it doesn’t. And, with the Clearer Audio Silver-Line Optimus Reference 75, everything really worked in harmony. Instead of that knife-edge between too flat and too edgy, the cable helped create more of a balanced platform of digital audio. By this, I mean the cable didn’t necessarily bring a sense of order on the sound (because in the main it was well-ordered); instead it helped keep the sound ordered for longer and across a wider range of musical styles. This is no small feat; the combination of CD and DAC – though often excellent – is capable of simply failing to shine on some discs such as ‘In Salah’ from Back Country Suite by the late, great Mose Allison [Prestige], which should just jump out of the loudspeakers but simply sounds a little too ‘digital transfer’ bright and overly clean. On connecting the Clearer Audio cable, the problem was traced to the interface rather than the album itself and it became more dynamic, refreshing, and exciting. Taking the interconnect out and replacing it with a very good cable of a few years hence, and that brightness came right back.
This is one of the interesting aspects of digital cable performance. It should do nothing to the sound, but the simple expedient of getting the links in the chain right help bring out the best in even a first rate system.
I hope Clearer Audio is able to introduce a wider range of connectors than just RCA for its top digital interconnect, if only because I can see this being used in the multitude of different digital connections around the back of a four-box dCS Vivaldi 2.0 digital system. Often, that task is taken on by cables like Nordost Odin 2 and, while an excellent cable able to highlight perfectly what the Vivaldi can do, the cost of the Gordian knot of cables used to wire these four boxes together can approach or even exceed the already ‘spendy’ cost of the player. Clearer Audio’s Silver-Line Optimus Reference 75 is more than up to the task and is certainly more than good enough to let any good digital audio shine. Despite the name being a bit of a mouthful, this cable comes firmly recommended.
Price & contact details
Product: Clearer Audio Silver-Line Optimus Reference 75 Digital Interconnect
Connections: RCA only
Price: £495/0.5m (£975/1.5m as tested)
Manufactured by: Clearer Audio
Tel: +44(0)1702 543981