Synergistic Research Cables Foundation SX (Full Set) Review

With the introduction of their Foundation SX line of cables, Synergistic Research artfully straddles that balance for those looking to step into the world of high-end cables.

Surveying the world of high-end cables, one is presented with an array of available choices in terms of design aesthetics and technical construction. All come with claims of providing the highest levels of fidelity when inserted into the bodies of our HiFi systems. These various strands of electrical connective tissue also come with pricing structures that range from the fairly reasonable to the eye-wateringly excessive. For those intent on entering this competitive (and occasionally controversial) arena of upgrades, how does one balance getting the best possible performance they need with the build quality, aesthetics, support, and other features they may want? Synergistic Research’s new Foundation SX line of cables looks to strike the right mix of all those elements at a price level that is not unreasonable for this category of products.

I do not typically do isolated cable reviews, due to all the variables present with the observations being less reliable. The Synergistic Research Marketing Team offered to let me review the Synergistic Foundation SX line from source to speaker cables. I find that I do not search for cables to do anything other than get out of the way and allow the music to emerge. Each of these cables managed to punch well above its weight class and deserves serious consideration at or well above its price category.

The Synergistic Foundation SX Cables manages to do several things very well that are not always appreciated. They have high-quality connector parts with their spades, RCA plugs, and XLR male and female connectors. All felt solid, and the surface did not scratch easily after tightening down. They were very flexible allowing for easy connections near wall boundaries with components pushed rather close.

The Synergistic Research Foundation SX cables are said to use trickle-down technology from the company’s top-tier SRX cables. Features like pure silver conductors encased in sealed air dielectrics which they call “Air String Geometries.” Another feature is something called a UEF compound that highlights the use of graphene on the connector bodies and strategically in the cable shielding. The company claims to use long-duration, high-voltage conditioning which purports to improve the signal flow. And, most intriguingly, Synergistic Research includes with each cable set two types of what they call UEF Carbon Tuning Discs.

These discs appear to the eye to be small rounds of carbon fiber with either a purple or gold colored label on one side. The idea is to attach a disc to an output connector’s body, just before it meets the wire (let’s use the RCA output connectors from your CD player for example). The discs are affixed with a small dab of included white tack (feels like blue tack) material. The UEF compound on these discs is supposed to interact with the UEF compound on the cable connections, affecting the electromagnetic field around the cables and thus improving the sound.

The company claims the Foundation SX cables alone are tuned for a neutral sonic presentation. Adding the gold discs gives a more holographic presentation while the purple disc is said to increase a sense of clarity. The overarching idea is that using an entire loom of Foundation SX cables and, by extension, the Carbon Tuning Discs throughout an audio system will best demonstrate the sonic improvements. The SX cable package had a very refined sound and did not reveal any areas of weakness. They should be put on the short list of cables to review in a system consisting of one brand. They were very complimentary of each sonic presentation.

The setup was done in a room with a high ceiling, and the wall behind the components was heavily treated with Auralex acoustic tiles from floor to ceiling. Two corner traps, per side, also by Auralex were utilized. Sidewall deflection was also implemented at the first reflection point to reduce smearing. Factory spikes were used under my Acoustic Zen speakers, and they were placed four feet from the rear wall, toed in slightly at a neutral vertical angle. Line conditioning was provided by a restored Audio Power line conditioner plugged into a dedicated line utilizing solid core 10 awg copper romex, into an Audioquest pair of silver outlets. The AC power cord from the Audio Power unit is captive, and a custom power cord with a silver rhodium AC plug, with internal silver spades connecting the silver/copper Teflon wire to the AC plug clamping mechanism providing an air-tight connection.

Synergistic Research has been in the cable business for over 30 years, and with that history, an accumulation of technology has been trickling down into other lines of their cables as is the case with the SX line. The goal in developing the SX line was to design and build a line of cables at a modest price point in order to compete with other cables in a much higher price bracket. The cables on review here are the Synergistic Foundation SX speaker cables: interconnects in XLR configuration, RCA interconnects, RCA phono cables, USB cables, and a digital SPDIF cable. All are from the Foundation SX line. Speaker cables are in Bi-Wire configuration with the Bi-Wire transition occurring via Bi-Wire pigtails on the speaker end. Speaker cable terminations are low-mass silver spades, which appear to be soldered in place as opposed to crimp connections. They are reasonably flexible with a soft outer fabric. The spades appear to be high quality, low-mass, and appear terminated very securely with double heat shrink at solder joints.

Flexible, stranded wire becomes very brittle after solder is absorbed. Thus, the solder joints of the SX cables appear very well protected from repeated motion with the Synergistic dual-layer heat shrink which ensures low fatigue at the solder location. I have seen cables improperly secured without heat shrink causing cable strands to crack and lose part of their conductive medium. Many manufacturers use adhesive-lined shrink (usually polyolefin) which secures the connection and minimizes fatigue, stops slippage, and just feels secure with minimal bending possible.

All connections were cleaned with a cloth wipe. No surface contact solutions were used. All the cables were burned in prior to listening and bi-wired into my Acoustic Zen Crescendo MKII loudspeakers. Amplification was performed by a custom-engineered tube amplifier of a push-pull, ultra-linear triode with dual KT150 tubes in the output. Minimal feedback was utilized.

The Synergistic SX speaker cables were used in place of mine, which have silver rhodium spades. The SX cables did have a very different presentation, however. They had a focus on the midrange with a great sense of presence and palpability. Female vocals were treated with a wonderful delicacy and a decrease in sibilance and grain compared to mine. This is a cable for one wanting a smooth, palpable midrange with a staging of the singer slightly in front of the band with the rest of the band behind her.

Using the tuning discs with adhesive had the purple extending things on the bass and treble while the gold gave a sense of a bit warmer, more palpable textured reproduction. The tuning dots are for fine tuning and, at first glance, they look like they cannot work due to how small they are but they seem to do something. You will have to experiment on your own and make your own evaluation and assessment. The Synergistic Foundation SX speaker cables deserve a High Recommendation for the next speaker cables to put on your “cables to evaluate before buying” list.

Next up is the Synergistic Foundation SX Balanced interconnects. They use a metal XLR housing of very high quality with silver contacts and solid build quality throughout. They were plugged into my Pass XP 20 preamp. These are, in short, very good-sounding interconnect cables reminding me of some of the great cables I have heard that have been in the over $2,000.00 range.

My Silver cables thinned out the upper female vocals and added distortion to the sibilance. The tuning dots can be used to push things a little more detailed and articulate or a bit warmer. I liked the purple dot which seemed to give just a bit more air and detail. Depending on your own system, the effect may vary. The difference is subtle and will not make a bad cable into a world-class cable but is worth trying to see if the changes fit your system needs. A similar result was obtained using the balanced SX with my updated Bryston 4BSST driving Magnepan 1.7 speakers. The SX proved to be very good cables for under $2,000.00.

Naturally, I followed these up with the Synergistic Foundation SX RCA terminated interconnects which have quality RCA plugs and silver surfaces. One difference is that now I am going to insert my Quicksilver M135 amps with new el34 tubes in the mix. I have some new el34C tubes from Psvane. Tubes are hard to get these days, but Psvane seems to be making these without any issues. I bought mine from Antique Electronics with Apex matching. My previous el34 tubes were from Valve Art. They were manufactured by Shuguang which closed years ago. The Psvane factory is made up of key former employees of the Shuguang factory. Comparing the tubes is another story but I can say they are more dynamic than the Valve Art which was very mellow. The Psvane are more alive from top to
bottom, pushing the boundary of “too” alive, but more detailed and dynamic.

The amps matched very well with the SX cables. They were very detailed and dynamic with stellar bass and beautiful harmonics. I really could find no fault with them and they were very musical. They were just superb cables that got out of the way and allowed the harmonics to pour out. It was hard to pin a character on them as they were very neutral sounding in this combination. A stellar interconnect that deserves an audition.

Next up was the Synergistic Foundation SX USB cable. This was used going into my Luxman DA-06 DAC. I took out my Oyaide USB cable which I have been very happy with. Initially, after putting the Synergistic Foundation SX USB cable in, things were shifted to more detail. They were very vivid, too much, in fact, (I was using my silver cables) and I went immediately to the gold disc and things calmed down just enough so the detail was not going over the top. The brightness was gone when I went all Synergistic.

The USB is a very fine-sounding cable. It was flexible and would likely fit well into a digital system that is neutral, slightly warm, and not tipped up. I am not sure the gold disc will be enough to change the sound enough if your system is already tilted in that direction. However, if used in combination with the other Synergistic Cables there will be a much better chance of having a very good balance.

The Synergistic SX phono cable went into my Conrad-Johnson fully restored HV1A nuvistor phono stage with 28db of gain. No step-up transformers are used in the signal path, just tube gain. This plugged into a custom-designed and built phono stage patterned after the EAR 834 Signature with high-quality ODAM V-Caps, military-grade matched parts, point-to-point silver wire, and an Amperex Bugle Boy tube set.

The phono section was very good prior to switching out the cable, but this Synergistic Foundation SX really matched well and just settled in with a very large, expansive stage, wonderful depth, and very tight, full, driving bass lines that were just visceral. It’s an easy must-audition phono cable for anyone shopping for a cable in this price range or much higher. It was just a very solid performer that made no mistakes and gave up very little to the more high-dollar phono cable.

My VPI Classic was very happy with this phono cable as was the rest of the playback phono system. I have tried perhaps 8-10 phono cables. Each one had some things they did well and some things that were lacking. The Synergistic is perhaps the most complete-sounding phono cable I have tried at even up to 2 or 3 times the price.

Overall, my impression was very positive with this group of cables, the Foundation SX from Synergistic Research. They are Cables that should get an audition if you are spending anything near their cost or more. We all know cables are very system and component-sensitive and need an audition to really hear what they can do.

The Synergistic Foundation SX cables provide a high level of resolution and refinement, without needing to spend a sum reminiscent of passing a kidney stone. They are not the best I have heard, but they get closer than their price suggests.

I am a big believer in keeping cables in a system from the same manufacturers to reduce variations in connector metals, and conductor types, and to keep a similar “house sound” with fewer variables. I am not opposed to a mix of brands, but I would first try all one brand before trying other brands and go from there.

Synergistic Research has a very good in-home audition offer which is the only place that really matters. You can hear them and make your own decision. That is a very generous offer and shows a very high degree of confidence Synergistic Research has in its technology and system integration diversity. I hope more cable manufacturers adopt this approach and allow more audiophiles to hear for themselves how a different cable performs in their system and move our sound just a little closer to live music.

In conclusion, the ultimate question is whether the Synergistic Foundation SX cables contribute enough to the musical experience and bring the listener closer to the musical event. I have found them to be so musical that I will be asking Synergistic Research for an extended evaluation so a few friends of mine can see how they compare with their costly cables and use them in future reviews. They are very good musical components and deserve an audition.