Over the past two years, I’ve written about several products from Crystal Cable and Siltech. Crystal Cable’s Art Series Monet speaker cables and Diamond Series phono cable impressed me greatly. Back in the spring of 2024, I hopped a plane to Santa Fe, New Mexico, to visit the Monarch Systems Distribution folks for their unveiling of the Master Crown series of cables from Siltech.
And just recently, I invested a good amount of time evaluating the several ways in which a full set of Siltech Royal Single Crown cables settled into my system. First, I reviewed the speaker cables. Then, I addressed the insertion of power cables and interconnects. Finally, I wrapped it all up by converting my turntable to Royal Single Crown.
Siltech and Crystal Cable are part of International Audio Holding, which is also the parent company of HMS Elektronik (a more affordable cable brand) and Sphinx Audio Engineering, which I’ll get to shortly.
I’ve been very interested in Siltech and Crystal Cable products, given some extremely positive experiences in my listening room. However, just this past May, at High End 2025 in Munich, I was ambushed by a pair of Element 5 speakers, the larger of two models that Sphinx Audio Engineering was showing. The smaller Element 3 was on static display. The Element 5s blew my skirt way the heck up, looking and sounding better than speakers from a cable company had any right to. That said, I was impressed by Crystal Cable’s Arabesque speaker when I reviewed it back in 2009, so I guess I shouldn’t have been quite so surprised.
I’d already booked a flight to Europe for July. After experiencing the Sphinx speakers, I made sure to contact Viktor de Leeuw, managing director of International Audio Holding, to see if I could stop by and take a peek at where it all happens. My timing worked out well, and we made a date.
Sphinx Element 5 speakers at High End 2025
International Audio Holding is located in Elst, a small town in the Netherlands, about a 90-minute train ride from Amsterdam. While Elst has a population of only 22,000, it’s quite literally just around the corner from Nijmegen, which is a fairly large university town that’s got a bustling center and tons of hip restaurants.
The plan was to spend two days hanging around IAH’s facility, putting in pretty much equal time investigating the cable end of things and getting a close-up of the new Sphinx speakers. I was staying at an extremely funky hotel—the Rebyl—that was a converted school with interesting architecture. The huge double-height ceilings made it easy to see that this was an institutional building before becoming a hotel.
IAH is headquartered in an unassuming industrial unit that’s far deeper than it is wide. Entering through the front door, I was pleased to see a bunch of SoundStage! Product of the Year trophies in the lobby, including one based on my review of the Crystal Cable Arabesque speaker.
IAH has been in this location for 30 years. The building was expanded in 2019, but the company is growing fast. “We’re bursting out of this location,” said Viktor. “We may have to buy a neighboring building if we can, or maybe we will move. If we do move, it will have to be local, as we value our staff—they are our most important asset.”
While the open central area was dedicated to all aspects of cable manufacture, a quick loop of the periphery revealed that there was much more going on. Two of the larger office spaces hosted activities only obliquely related to cables. In one of the larger workshops I encountered Mario Licanin, the acoustic R&D engineer responsible for much of the design of the Sphinx speakers. Here there were completed speakers, a single cabinet in a state of undress, and lots of parts—along with measurement equipment.
Right next door, I found a sparse, orderly office entirely devoid of cables and speakers. This was the domain of Kingston Zhou, Siltech’s dedicated R&D engineer. While young Viktor has assumed responsibility for the day-to-day operations of IAH, his father, Edwin van der Kley Rynveld, the founder of IAH, is still actively involved in the company in a technical-lead role. Kingston works with Edwin on advancing the company in areas that aren’t typically associated with a cable company.
A short history lesson: although not commonly associated with the IAH brands, electronics and speakers have been produced under the Sphinx Audio Engineering name since the mid-1980s. Of course, cables from Siltech and Crystal Cable have long been the bread and butter of IAH, but the company has always produced a full range of audio products.
And now, Edwin has been freed up to pursue these ancillary avenues alongside Kingston, Mario, and—soon to come—an additional engineer who will be starting with IAH shortly. This team is important because, as I found out the deeper I dug, IAH is working on some extremely interesting technologies.
On the face of it, the cable business is fairly straightforward. You get wire, terminate it, and box it up. But after touring the main assembly and production area, it became quite clear to me that it’s not that simple. IAH has made significant investments in technology, including dedicated braiding, measuring, and taping machines. But its main resources are its raw materials and its workers.
First Siltech and then Crystal Cable have long worked with silver as their raw material, and the differing grades of silver—their G9 Silver-Gold Alloy and S10 Monocrystal Silver—are unique to the company. These are precious metals, right? So of course I asked to see the raw goods. Viktor led me to a locked storage area and opened it up for me to have a peek. Inside were spools of wire, looking rather uninspiring. I guess I was expecting something piratey, glinting like treasure. Still, that cabinet held a fair amount of silver.
“How much is in there?” I asked, not sure how Viktor would frame the answer. He was cagey. “The raw wire sells for about two to three times the spot price of silver and gold. And then there’s additional processing cost,” he responded. “It’s a big expense, and we really hope the price of metals doesn’t rise.”
I saw many instances of bare silver wire on my rounds, and I found it odd that it was always clean and bright. I asked about this. “Pure silver doesn’t tarnish,” Viktor responded. “It’s the impurities that cause tarnish, and that have given silver cables a bad name. Our cables remain stable over time, and that increases retained value.
“We source 90% of our parts from the European Union, mostly from here in the Netherlands,” he continued. “Our conductors are from a European partner company. They have metallurgists who we work with to build conductors.”
So that’s the raw wire itself. What was also obvious was the feeling of quiet dedication on the shop floor. All the workers were busy, each doing a different job, but they were unhurried, measured in their movements. There was much happening—soldering, winding and braiding of raw cables, construction of terminal blocks, finishing and packaging. But there was a sense of purpose. Clean, too—everything was tidy. The high-quality tools were neatly racked at every workstation, with no bits or garbage lying around.
“Our staff rotates their tasks, so that each person can do any task. It’s important for continuity, and it’s also important that nobody gets bored,” Viktor explained when I mentioned the calm environment. “We have a good mix in our production team,” he continued. “One lady has been here for 27 years. Some are real audiophiles who had sought out the opportunity in the company. We take good care of keeping a good atmosphere.”
As part of my day, Viktor had arranged for me to build a set of my own cables. A clever plan on Viktor’s part, as this would involve me in every aspect of the production process. My task was to construct a pair of Siltech Classic Legend 380i RCA interconnects, and my mentor was Laura Rijnveld, who I got the feeling had guided more than a few journalists through this process.
The first task, one that wasn’t a standard production activity, was to custom-engrave my name on the side of the large barrel that’s attached to the receiving end of the cable. IAH has its own laser-etching device, which they use for the connectors and attachments on their various cables. While the programming to add my name was already set up, from watching it in action I gathered that the device is fairly flexible in its use.
I’ve made my own RCA cables before. I have a soldering station and third-hand clamp, and I’ve used Canare Star Quad to build subwoofer cables both for my own use and for friends. That said, it’s been a long time since I’ve done that, and the onset of serious carpal tunnel issues in my hands had me somewhat dubious about how well I could accomplish this task. Regardless, it sounded like fun, and I was ready to give it a go.
I sat down beside Laura, who had already arranged our tools and parts. Laura then pulled up a document on the workstation’s monitor that listed step-by-step instructions for this specific cable. “There is a separate document for each cable,” Laura explained. “This helps ensure consistency, no matter which person is making it.”
The granularity of the instructions was impressive. Each step was clearly outlined, with text and photos. So long as we followed each step in series, there was little room for error. That’s not to say it was easy.
When I had made cables in the past, there were three steps in the process that I found extremely fussy. The first was stripping the insulation from the individual conductors, which are tiny and delicate. It takes a careful application of pressure to remove that insulation without cutting the conductors. Many times, I’d screw it up and then have to strip even more off the outside jacket. And no matter how many times I did this, the exposed conductor was still too short. But by watching Laura’s steady hands and listening to her clear instructions, I managed both ends of both cables without ham-fisting it.
Another failure that had repeatedly haunted me was forgetting to put the RCA connector’s barrel over the cable before soldering the jack itself. I’d complete the cable and then notice my error, being forced to un-solder it, remove the jack, and do it again right. The step-by-step documentation rendered this an impossibility.
But the most problematic part of the process for me was always the actual soldering. You have to sufficiently heat up the connector in order for the solder to flow correctly. Too cold and it just blobs up, overflowing and causing a short between the positive and ground connections. Too hot and insulating parts inside the connector start to melt. Again, Laura guided me through this task and I got it done, but my set looked far less tidy than hers.
There were many more steps—tighten the sheathing; heat-shrink the connections; attach the barrels. It was clear to me that I was being far from efficient at my end of things, and it took us much longer than it would have for Laura alone. Still, getting my hands dirty in this way gave me much greater appreciation for the care and consistency in IAH’s cable construction than any passive tour could have done.
Now that we had built the cables, we headed over to the testing area. IAH has built a computerized workstation that tests numerous electronic parameters in one pass. Plug each end of the cable into the connectors, choose the appropriate cable model from the drop-down list, and the machine runs the tests. Laura’s cable obviously passed, and I was relieved that mine also came through clean.
Our next task was to attach the NFC tags to the cables. Laura entered my name and the cable’s serial number into the code and downloaded it into the tag. She scanned the completed tag in the Siltech app on her phone to show me how I could register the cable.
The last step was quality control and packaging. I handed over my cables to the QC officer, and he examined them closely. He looked disapprovingly at a couple of scuffs on the barrels and cast a gentle stink eye at me. My work obviously wouldn’t make it through this stage, but I was a guest, so he let it pass and boxed them up.
Believe it or not, it was quite tiring building those cables. I hadn’t done anything like that in years, and I found that hours of concentration (yes, it took me that long) left me feeling drained. It was the end of the day anyway, so we packed it in.
Next morning we took a more sedentary approach. I mentioned earlier how impressed I was with the Sphinx Element 5 speakers when I’d heard them at High End 2025. That was under show conditions, which are typically far from ideal; I was keen to hear how they would sound in IAH’s dedicated listening room. First, though, I had a chat with Mario Licanin. We delved into the guts of the Element 5 speaker, which is ostensibly a transmission-line design. That said, Mario had some things to highlight about this type of bass alignment.
“The Element was a two-year project,” he told me. “We started by unearthing all of the old, sometimes ancient, documentation on transmission lines. There are many old documents, and they are often contradictory, but we used those as a basis and experimented from there.”
Mario started with ABS pipes of different lengths and with varying fills and tapers. “Once I had the data I needed, I built an electronic model. Eventually I built a prototype, which ended up as Element 3.” And here’s a crazy idea—the woofers in the Element speakers are powered, but not fully. They draw some power from a built-in class-D amp while remaining in direct connection to the upstream external power amplification. “This is our PAC, our Passive/Active Crossover. As a result, the speaker has interesting specifications—94dB sensitivity and 16-ohm impedance. It’s exceptionally easy to drive.
“We built many prototypes,” continued Mario. “But our first focus is to get the Element 3 and 5 ready for market. There are more speakers coming. We are planning an Element 7, which will be even larger, with more drivers.”
A very early protoype enclosure
I mentioned the amplifiers that were used in Munich, which were branded under the Sphinx name. “Yes,” said Mario, “we will be building production amplifiers, hopefully ready by 2026, but we have much work to do.”
With that, we headed into the listening room, which was a large, well-damped space. The Element 5 speakers looked a touch lost up front of that spacious room, but they also exuded elegance, and would very likely fit in just fine in a luxurious home. This was much the same system I’d heard in Munich, fronted by Sphinx electronics.
It didn’t take long to conclude that my first impressions in Munich were correct. This speaker is smooth, defined, and rich. Listening to “Fight” by the Tragically Hip at loud rock levels was eye-opening. These speakers were evocative and detailed, while also sounding utterly free of stress.
We continued to talk between tracks. Viktor reiterated what Mario had said. “We are building amps under the Sphinx name, slowly building up the Sphinx line, and amplifiers will hopefully come in 2026. But we have lots of work to do.”
As we listened, I asked about the development process for both cables and speakers. “We always evaluate products at local dealers and try our products with their systems,” Viktor said. “We want to make sure our products match all equipment.”
As a proud, frostbitten Canadian boy, I played some Rush. I had mentioned Rush to several people earlier, and discovered that not one person I met at IAH had ever heard of them. It was like I had been transported to another dimension where they’d never existed. I played “Tom Sawyer” and got pitying, condescending looks.
An Element 3 with Element 5s to the side
No matter. Every track I played through the Element 5s sounded superb. No need to list them all, but Piazzolla’s “Milonga del Angel” was so juicy and emotional—huge reach in the bass, along with an extended but silky grain-free treble. These modestly sized speakers effortlessly filled that large space with tight, well-controlled bass. At an estimated €70,000 per pair, IAH should have no problem selling this elegant, excellent-sounding speaker.
I watched Mario switch the Element 5s out with Viktor’s help. At 55kg each and fairly slippery, this was definitely a two-person schlep. In came the Element 3s, smaller, just a little tidier in appearance, and definitely my favorite looks-wise.
The little guys—not that small, really, especially given their high-density stone-encased enclosures—had much the same sonic profile, which was no real surprise, given that they use the same technology and drivers.
The main difference was in the low end. The Element 3s sounded physically smaller. Again, no surprise here, as the smaller speaker has only one bass driver. Images were also slightly more recessed, which resulted in a more enticing, intimate presentation. Just as immersive, though. On busier, more demanding music, the Element 3s were missing some of the scale of the big boys. Like I said, this was a fairly large room, and well damped, so Rush at high volumes sometimes felt a tiny bit lost. I think they would be perfect in my smaller room.
The rich, creamy marble finish and organic humanoid form of the Element 3 is stunning, and I preferred it to the larger Element 5. This speaker is something I’d expect to see in the British Museum’s Egyptian section.
Just to mix it up, Mario and Viktor moved the Element 5s back into the system.
I cued up Faith No More’s version of “War Pigs.” Holy hell, what incredible reach and slam. It was like the Element 5s weren’t even breathing hard. Still pushing Rush, I played “YYZ,” and the complexity of the music was clearer, with more definition in the bass, more presence. The reach in the bass remained superb. It felt obvious that—in this room—the Element 5 was the superior speaker, but with two dedicated midranges and woofers, it should be.
To round out my day I put on my old systems-analyst hat and sat down for a technical talk with Kingston Zhou. During my IT career, I often found that the smartest people in the room were the quietest. As we began to chat, I got the feeling that this was one of those times.
IAH has done a clever thing—they hired Kingston and gave him what seemed like complete intellectual freedom. What I mean by this is that they didn’t say, “Design a better cable,” or assign any other concrete task. And given that he’s not an audio guy by trade, Kingston took a unique path toward determining how to make audio gear sound better.
This is really interesting. Kingston designed a process by which he could encode a piece of a music file and generate a spectrographic image. The system could encode an entire track or a piece of a track. In this way, he could examine a specific piece of the music, homing in on parts that sounded especially good or bad on a system and determining what actual physical, visible components of the sound in that portion sounded good or bad.
Kingston Zhou
It gets better. Kingston also created an algorithm that could record and process the actual output of the speakers for that same track. And this is the best part: it would then be possible to compare the spectrographic images of the played music to those on the source track. This process could be used with short, sub-second samples for specific uses, or with larger, longer samples to quantify parameters directly related to listening satisfaction.
We took a deep dive into the results of this comparative process. Kingston showed me synced-up snippets of music, with the top trace showing the music file itself, and the bottom trace showing the recorded playback. We looked at recorded playback from two different speakers, and it was clear that one speaker’s output was closer to the original sample. I’ve thought about this process a fair bit since I returned from Europe, and I can see huge potential for this, although many confounding variables need to be standardized. But still—this is fundamental research into what makes a system sound good. It’s new, and it’s intuitively valuable.
Kingston was exploring several other avenues as well. As IAH is a cable company at heart, it made sense that he was doing lots of modeling of cable values, such as inductive crosstalk versus capacitive crosstalk. We did chat about that, but I was becoming saturated, and it’s not my specialty. Still, it was clear that his research, while tangential to immediate applications, would likely bear long-term rewards.
At the end of my tour, I was left with far more to think about—and write about—than I’d anticipated. I had discovered that what was ostensibly a cable manufacturer was actually much more. While the cable end of things alone gave me plenty to work with, given the company’s tight processes, the speakers, amplifiers, and theoretical research were the wild cards.
The Crystal Cable and Siltech products I’ve reviewed have impressed me greatly, but the Arabesque speaker I evaluated 15 years ago should have prepared me for those surprises. I’m hoping to get a pair of the Sphinx Element 3 speakers in for review this fall, so the story will continue. Stay tuned.
Jason Thorpe
Senior Editor, SoundStage!
