Stein Music Super Ground Cube

by Dawid Grzyb / August 14, 2026

Stein Music Super Ground Cube is the German company’s top-shelf grounding solution and our subject this time around. Enjoy!

Mr Communicator

During this year’s HIGH END Vienna gig, I came across one of those companies that most attendees would probably glance over and move on, or perhaps omit altogether when compiling their mental list of the show’s important exhibitors. This wasn’t because its products were uninteresting. Quite the opposite, actually. The reason was much simpler: unlike the overwhelming majority of audio houses present at the Austria Center, Stein Music wasn’t there to show off another amplifier, DAC, streamer or pair of loudspeakers. Its stand was populated largely by accessories, as this is where the company specialises. Such products are a peculiar breed in high-end audio. Some are taken very seriously, some are treated as harmless fun, while others are dismissed before anyone has even bothered to find out what they actually do. That makes a company such as Stein Music particularly easy to overlook at a show where enormous loudspeakers, exotic turntables and amplifiers the size of small refrigerators compete for attention. Yet I knew better than to walk past.I’ve been aware of Stein Music for more than a decade, in fact since before this website had even launched. The reason for that is rather personal. The company that made my first serious pair of floorstanders, Boenicke Audio, had been using Stein Music products inside its loudspeakers. Sven Boenicke has never been shy about experimenting with solutions he considers capable of taking his designs further, and Stein Music’s components became part of that equation. Various Boenicke models from the highest-tier SE+ range feature the Stein Music Speaker Match Signature. As the owner of Boenicke W11 SE+ speakers, I’ve been enjoying the benefits of these components in my own system for years. With some effort I could probably remove these bits and see how my W11s fare without them, but nobody sane would do that. Speaker Match Signature modules are part of the Swiss design, and that’s that.

If an established loudspeaker designer such as Sven Boenicke decides that particular components or treatments are worth incorporating into the product itself, rather than simply leaving them as optional external accessories, that tells us something. It doesn’t automatically validate every claim made about them, of course, but it does make their maker worth investigating. And so, with Stein Music making its debut here at HifiKnights, it seems only fair that before getting to the device at hand—the Super Ground Cube—we spend a little time discussing the company behind it. Because once one looks beyond the sometimes unusual appearance and terminology of Stein Music’s products, its history turns out to be considerably more conventional and grounded in practicality than one might initially expect.Stein Music is a German audio house, founded in Mülheim an der Ruhr in 1982 by Holger Stein. The location is still the company’s home today, and the business has remained there since its inception. It is also still a family affair, having evolved from Holger’s early workshop activities into a full-fledged high-end audio manufacturer. The story starts well before 1982, though. Holger Stein built his first amplifier when he was only fourteen years old. By his own company’s account, the result wasn’t exactly a masterpiece, but the experiment established a direction that would eventually define his professional life. At eighteen he decided to study physics because he wanted to understand sound more deeply. During his studies he continued building, repairing and modifying amplifiers and loudspeakers for fellow students. What began as a technical fascination and workshop activity gradually turned into professional work, and in 1982 the hobby became a company.

That sequence of events is worth keeping in mind when looking at Stein Music today. Holger Stein didn’t enter high-end audio from the marketing side, nor does the company’s history begin with an accessory invented to exploit the latest audiophile fashion. Its roots are much more basic: a young man builds an amplifier, becomes fascinated by why it sounds the way it does, studies physics in an attempt to understand the problem, and then spends decades investigating the consequences. In that respect, the company’s rather unconventional present can be traced directly back to a very conventional starting point: curiosity about how things work.This also helps explain one of the more unusual aspects of Stein Music. The company doesn’t appear particularly interested in adhering to the conventional boundaries between audio categories. A manufacturer that began with amplifiers and loudspeakers eventually developed cables, power products, grounding solutions, resonance-control devices, room-tailoring components, vinyl accessories and a wide assortment of what Stein Music calls its Essentials. Its current catalogue consequently covers a remarkably broad spectrum of audio-related designs, from conventional stuff to solutions aimed at the less obvious aspects of system performance. There is, however, a logic to that apparent madness, and it has little to do with simply wanting to have a product in every conceivable category. Holger Stein’s approach is fundamentally systemic. Stein Music’s own description of its philosophy repeatedly comes back to the idea that convincing music reproduction requires looking at the complete listening chain rather than treating a loudspeaker, amplifier, cable or room as an isolated entity. The stated objective is not simply technical perfection in one particular product type, but the company’s interest in everything from the audio system’s key building blocks to what happens around them. This is the point where Stein Music starts becoming particularly interesting.

It should also be clear that Holger Stein is, first and foremost, an engineer-minded audiophile with a background in physics. That distinction matters because his products have often ventured into areas that conventional high-end audio tends to leave alone. Over the years, his interests have included familiar engineering subjects such as circuit design, loudspeaker behaviour and resonance, but also less conventional questions involving electromagnetic fields, mechanical energy, materials and the behaviour of the listening environment. That broad curiosity has shaped Stein Music’s product development. Some of the resulting designs are straightforward enough to explain using established electrical or mechanical principles. Others involve hypotheses and mechanisms that sit considerably further away from the territory of conventional audio engineering. That mixture is probably one reason Stein Music has attracted both committed followers and healthy scepticism over the years.The evolution of Stein Music is essentially the evolution of Holger Stein’s idea of what constitutes an audio system. If a loudspeaker has mechanical resonances, those resonances can influence its behaviour. If a crossover contains components that themselves behave mechanically, they become part of the equation. If a cable interacts with the electromagnetic environment around it, that may be worth investigating. If an amplifier and loudspeaker form a particular electrical load, perhaps the interface between the two deserves attention. If the room itself contributes an enormous portion of what eventually reaches our ears, then conditioning the room becomes no less relevant than changing the amplifier. Whether one accepts every explanation Stein Music proposes is a separate matter. What is difficult to dispute is that the company has built its entire existence around looking for effects that may sit outside the obvious signal path. This is also why products such as Stein Music’s Speaker Match actually exist. On paper, the idea behind this one is hardly exotic: it incorporates a Zobel network, so a familiar electrical arrangement that can modify the impedance behaviour of a loudspeaker and, according to the company, reduce high-frequency distortion and intermodulation associated with electrical interference. But Stein Music doesn’t stop there. The device is also built around what the company calls its Resonance Control System, which is intended not to damp resonances but to stabilise them without removing what Stein regards as useful musical energy. That distinction—damping versus controlling—is quite representative of the company’s thinking.

Rather than simply trying to eliminate every measurable phenomenon that looks undesirable, Stein Music often asks whether the phenomenon itself can be managed in a way that preserves what it considers musically useful. It is an approach that appears again and again in the company’s products, from mechanical interfaces and resonance-control devices to room treatments and grounding solutions. And this is where the apparently bizarre catalogue begins to make sense. The company isn’t really organised around the conventional hierarchy of “source, amplification, loudspeaker.” It is organised around the idea that everything matters because everything is part of the system that we, listeners, ultimately experience.This distinction is important because Stein Music can easily be mistaken for an accessories company. It isn’t. Its current catalogue contains complete loudspeakers and amplifiers, alongside vinyl hardware and the extensive Essentials range. Its loudspeakers are not afterthoughts designed to provide a reference platform for its accessories, either. Think variously sized horn systems that combine open-baffle bass with horn-loaded sections and, in the more ambitious designs, active subwoofer arrangements. All in all, those are serious affairs. The same goes for its electronics and analogue products. Over the decades Stein Music has produced amplifiers, phono stages, cartridges, turntables and other conventional audio hardware, while simultaneously developing products that are much harder to put into a familiar category.

That breadth is useful when considering something like the Super Ground Cube. It isn’t coming from a company whose only contribution to an audio system is a mysterious little box that somebody is supposed to plug into a spare socket and hope for the best. It comes from a manufacturer that has spent more than four decades building complete audio products while investigating what happens when seemingly minor elements of those systems are altered. Stein Music says it has manufactured in Germany since its foundation, handling the process from initial concept and prototype development through assembly and quality control. The company describes itself as an owner-managed family business and a manufactory rather than simply a brand outsourcing finished products elsewhere. Holger Stein remains its chief developer, while the next generation is involved in the business as well. My contact at Stein Music was Sebastian, Holger’s son, whom I also met manning the company’s booth in Vienna. Let me stress that, despite its sometimes esoteric reputation, Stein Music isn’t some recent boutique operation that appeared because the high-end market discovered a taste for exotic accessories. By the time many of today’s better-known audio brands were still getting started, Holger Stein had already been experimenting with sound for years.Come to think of it, there is something almost stubborn about Stein Music’s longevity. For more than four decades, the company has continued to investigate the spaces between the obvious building blocks of an audio system, venturing into both conventional engineering territory and considerably less familiar land… and it’s still around. Its catalogue is therefore difficult to summarise without making it sound either more ordinary or more eccentric than it really is. Perhaps the fairest way of looking at Stein Music is as a company built around one question: what else is influencing what we hear? The answer, according to Holger Stein, is a great deal more than just the electrical signal travelling from source to amplifier to loudspeaker. Some of the underlying ideas of this philosophy are easy to understand. Others require considerably more explanation, while some venture into territory that will inevitably strike technically minded audiophiles as far-out. Stein Music itself has gone as far as describing some of its more recent room-acoustic work in terms of quantum-physics-based technology, a claim that is certainly more ambitious than the language normally used by mainstream audio manufacturers.

Yet perhaps that is precisely why the company deserves attention. At HIGH END Vienna 2026, Stein Music reported that its products were used in four demonstration rooms, including systems from Clarisys Audio, Absolare, Aurender and Audioware. The products involved ranged from the Super Ground Cube and Ground Cube Silver Signature to Acoustic Discs, H-Pro and power products. That doesn’t prove that any particular Stein Music accessory is responsible for the sound of those systems. Nor should it. High-end audio demonstrations are complicated chains in which dozens of variables interact. But it does illustrate something important about the company’s position today: Stein Music’s products are not confined to its own systems. Other manufacturers and system builders are willing to incorporate them into serious demonstrations. And this takes us back to where I started.Let me stress that Stein Music’s stand in Vienna was easy to overlook precisely because it wasn’t shouting for attention with a giant pair of loudspeakers or an intimidating stack of electronics. Yet the more I think about it, the more appropriate that seemed. Holger Stein’s work has never really been about one spectacular component. It has been about the things surrounding it, the things touching it, feeding it, grounding it, supporting it and interacting with it. In other words, the things that are easiest to ignore. And perhaps that’s exactly why Stein Music has managed to remain relevant for more than four decades: there are people who have incorporated its ideas and products into serious systems because, in their experience, they make a difference.

All this also means that before judging what today’s particular box does, we have to understand what Holger Stein believes an audio system actually is. Because if an amplifier is an amplifier, a loudspeaker is a loudspeaker and everything else is merely an accessory, there isn’t much of a case to be made for Stein Music’s philosophy in the first place. If, however, an audio system is a complex physical environment in which electrical, mechanical and electromagnetic phenomena constantly interact, then the little boxes sitting around the big ones suddenly become considerably more interesting. And that’s exactly where the Super Ground Cube enters the picture.Before we get into what the Super Ground Cube does, it is worth establishing what sort of problem Stein Music is trying to address. Modern homes are electrically busy places. Digital circuitry, switching power supplies, network hardware, computers, displays, routers, battery chargers, light dimmers and an ever-growing collection of other household electronics all contribute various forms of electrical interference. Much of this activity takes place well above the audio band, which doesn’t automatically make it irrelevant. High-frequency noise can find its way onto signal and ground paths, interact with circuitry and ultimately affect the conditions under which the actual audio signal is handled. We may therefore think of our audio systems as operating against a higher noise floor than they otherwise might if the electrical environment around them were quieter.

This isn’t a new observation, nor is Stein Music alone in trying to deal with it. Computer Audio Design, for example, developed its Ground Control products specifically around high-frequency noise present on signal ground and mains earth. CAD’s approach is particularly straightforward to describe: its passive Ground Control boxes contain a proprietary composite material structure designed to absorb high-frequency energy and convert it into heat. The company specifies an operating range extending from roughly 700kHz to beyond 10GHz. In practical terms, the box becomes a sink for unwanted HF energy, with the connected cable providing a path between the audio component and that sink.The CAD example is useful here because it gives us a clear reference point for understanding this product category, but it shouldn’t be confused with Stein Music’s approach. The two companies are dealing with broadly similar territory—unwanted high-frequency energy associated with grounding and the electrical environment around audio hardware—yet they don’t describe their solutions in identical terms. Stein Music’s Super Ground Cube isn’t presented as a device that simply converts HF noise into heat. Instead, the company describes it as creating its own “quiet reference potential”, giving unwanted interference somewhere to dissipate without relying on an already busy mains-earth network.

That distinction is important because the word “grounding” can make the Super Ground Cube sound simpler than it actually is. This isn’t a conventional earth connection whose purpose is primarily electrical safety, nor is the Cube powered from the mains. It is a purely passive device, and its job is instead related to unwanted electrical energy present around the audio circuitry. In Stein Music’s terminology, the aim is not to establish a connection to earth but to provide unwanted noise with somewhere specific to go. The company’s broader argument is that a quieter reference can help reduce the amount of electrical pollution circulating through the system and, consequently, improve the conditions in which the audio circuitry operates.The practical side is refreshingly simple. The Super Ground Cube is a 220 x 220 x 200mm box weighing 7.5kg, made in Germany and supplied with an in-house made multi-strand 1.2-metre connection cable that terminates in gold-plated beryllium-copper hollow banana plugs on the Cube end and connects to the system through the supplied WBT terminal. The product can be connected via a free socket on a power distributor, a wall outlet or alternatively to a grounded metal point via the alligator clip included in the set. The company also recommends orienting the device along the north-south axis, which is already a rather good indication that we have left conventional electrical engineering territory and entered Stein Music’s broader system-tuning philosophy. The small compass included with my sample should come in handy if a smartphone with a compass app isn’t within reach.

Physically, the Super Ground Cube is a nicely executed, reasonably sized object that doesn’t particularly want our attention. It looks very much like something intended to do its work somewhere in the background, quietly supporting the rest of the system rather than demanding a place in the spotlight. The enclosure is 3D-printed, and its surface shows; this is no audiophile jewellery, nor does Stein Music appear to have intended it as such. The overall appearance is utilitarian, very modest, and the way the thing has been put together feels honest. It’s mechanically firm, all in all solid, and gives the impression of a purpose-built tool rather than an ornamental high-end accessory. In that sense, its appearance tells us something about the intended audience. This is aimed at people who already know what a grounding box is supposed to do and are sold on the idea that, in a revealing system, such a device can make a noticeable difference. Those folks aren’t likely to need much visual persuasion.There is another curious feature on the box itself. A three-position switch allows the Super Ground Cube to be tuned to the system, with Stein Music describing the three settings in terms of warmth, openness and substance. In the middle position the presentation is intended to be primarily open and spacious, the upper setting adds warmth, while the lowest increases substance. In other words, Stein Music isn’t presenting the Cube as a purely binary device that either removes interference or doesn’t. It considers its interaction with the rest of the system sufficiently complex to warrant some adjustment, which also makes it rather different from a conventional filter. There is no display, no power switch, no active electronics and, importantly, no need to feed it from the AC supply. It simply becomes another passive element connected to the grounding arrangement of the system.

Of course, this immediately raises the obvious question: what exactly is inside the box that allows it to do all this, and possibly justify its rather steep €4’800 asking price? That’s the part Stein Music is less forthcoming about, although the founder did give me some rather interesting clues. He confirmed that the Super Ground Cube uses rare-earth materials and that an electrical contact is made to them, but unlike many grounding concepts that simply throw as much material as possible at the problem, Stein Music deliberately uses relatively small quantities. The reasoning is apparently less about brute-force noise absorption and more about preserving what Holger calls musical freedom. As a physicist, he has spent decades working with physical fields, and that this knowledge has found its way into the Super Ground Cube’s design. This, according to him, is also why he recommended orienting the device along the Earth’s magnetic field, which certainly isn’t something one encounters in conventional grounding hardware.There is also a refreshing degree of openness in Stein’s explanation regarding what we don’t know. He acknowledges that the effects of grounding concepts such as this aren’t yet completely describable by mathematics, with much of the development having been done empirically. He also points out that such devices can have an individual sonic signature: one grounding solution may suit a particular system beautifully, while another may limit fine resolution. In other words, Stein Music isn’t claiming that grounding is simply a matter of adding more material until the noise disappears. The type, quantity and implementation of the material all matter.

Holger stopped short of disclosing exactly which rare-earth materials are used, how much of them goes into the Cube, how they are arranged internally or what their electrical characteristics look like. There is therefore no conventional recipe here that would allow us to reconstruct the Super Ground Cube from a schematic or parts list. I can only speculate about one detail. Given that the Cube’s three-position switch determines its sonic behaviour, I can’t help wondering whether the rare-earth materials inside are combined or configured in three different ways, or whether three different materials are involved in the first place, but this remains merely my inference. What remains proprietary is precisely the part that would allow us to connect Stein Music’s description with a conventional engineering explanation. At some point, then, the paperwork ends and the listening begins—and that’s ultimately where I wanted to take this review.The general use-case scenario for the Super Ground Cube was as straightforward as they come. Just connect the product via the cable included in the box to a free outlet and enjoy the benefits. Well, almost. Technically, to put the loaner sample to work, I didn’t have to do anything beyond that, and when I wanted it off duty, I simply removed the banana plug from its WBT terminal. After each back-and-forth, however, particularly after connecting the box, I waited several minutes for it to collect whatever pollution it had to collect. Once it was disengaged, I listened immediately. This approach was largely due to my experience with CAD’s device, and it also meant that there was no need to power off my system even for a second.

To start somewhere, let’s return to my experience with CAD’s Ground Control treatment, which gave me a useful reference for what grounding hardware of this kind can do. The most immediate change was a darker, quieter backdrop against which everything else became easier to follow. Images were outlined more clearly, fine textures became more apparent, and the presentation gained a sense of fluency and openness. Transients tightened up, bass became more agile and controlled, while acoustic instruments benefited from greater momentum, richer harmonic information and longer, cleaner decays. There was also more air around performers and a stronger sense of spatial organisation, as if the system had simply become less burdened by something previously sitting on top of the music.Importantly, this wasn’t a case of adding brightness, sharpening the treble or otherwise altering the tonal balance. The character of the system remained intact; it simply became more explicit, cleaner and more dynamically free. At first, the tighter bass and increased speed could be mistaken for a slight slimming of the presentation, but extended listening suggested otherwise. What initially seemed like less body turned out to be less excess, with more of the recording’s actual textures, layers and transient information coming through. If Stein Music’s box worked along similar lines, I should hear a quieter backdrop, greater clarity and textural resolution, tighter timing, more spatial openness and, ideally, no obvious tonal penalty.

And that’s exactly what happened. In that sense, it would be fair to call the Super Ground Cube yet another efficient noise killer and call it a day, but doing so would severely undersell what this box did in my system. The usual noise-trimming was something I expected going in, so there were no surprises there. The Super Ground Cube handled that job well enough to leave me with no second thoughts about its potency. The interesting part was everything that came along with it. To explain what I mean, several music choices from my playlist will come in handy.Altın Gün’s “Niğde Bağları” is a fine slice of psychedelic funk, driven by a deep, elastic bass line, punchy percussion and wiry string textures. The track has plenty of snap and dynamic contrast, with the bass locking everything into a supple, physical groove while the psychedelic elements add colour and a slightly hazy, trippy atmosphere. On this track, the Super Ground Cube revealed extra punch from the drums, greater impact from the upper-register snap of the snares, and a beefier, more clearly outlined vocal line. Most notably, the space itself now felt more organised, three-dimensional and at the same time calmer, as if the box had expanded dynamic breadth, added heft, removed grit and made the whole view more articulated and easier to follow… all at once. The with/without delta wasn’t small by any means.

Eivør Pálsdóttir’s “Trøllabundin” from Slør is dark, atmospheric and deeply physical, built around her powerful, otherworldly vocal, a persistent low-end foundation and increasingly intense percussion. The bass has a deep, almost subterranean quality, while the spacious production gives the track a hypnotic, ritualistic character. This is my go-to fare for mapping virtually any change in the bass department, thanks to its combination of low-end depth, weight, texture and rhythmic drive. This pulsating bass, particularly with vented speakers, can and often does become overpowering in my listening room. With the Cube engaged, it was significantly more controlled, focused and impactful, to a point where I wondered whether such a wholly positive and rather drastic change would actually register on a frequency-response chart. Beats me, but the feeling was as if my ported speakers had suddenly lost their rear tunnels and developed larger side-firing woofers. The singer’s more articulated voice followed, also gaining extra on-stage presence, sensuality and vividness.Mike Oldfield’s “Five Miles Out” is a particularly busy, multi-layered piece, combining punchy drums, swirling synthesizers, electric guitar, keyboards and Maggie Reilly’s vocal with Oldfield’s trademark instrumental density. The 2013 remaster retains that packed arrangement while bringing out plenty of attack, rhythmic snap and dynamic movement; the drums have real physical punctuation, while the layers around them remain surprisingly easy to follow. It is also a good test of how well a system keeps complex passages organised, because when the music really gets going, there is a lot happening at once, with the possibility of the track losing its sense of order. Although I like this song because it takes me straight back to my childhood, my problem with it these days is that its most dynamically intense moments can descend into claptrap, losing elegance in favour of sheer impact that is less controlled than it should be. That’s why I don’t play it often. The Super Ground Cube remedied that by restoring the balance, introducing yet again a sense of calm and ease to the most charged passages. The most dynamic and intense parts remained every bit as energetic as before, but each snap, crack and hit now stood distinctly on its own rather than merging into a single, piercing mass of sound.

Alt-J’s “Breezeblocks” is a different kind of useful recording: rhythmically intricate, tightly produced and full of small percussive and electronic details that occupy a surprisingly dense arrangement. The clipped vocal delivery, elastic bass, handclaps, samples and sharply articulated drums create a restless groove, while the sudden shifts in intensity keep the track on its toes. It’s also one of those songs where timing matters enormously; when everything locks together, the track feels taut, immediate and almost physical, whereas any loss of separation or transient precision can make its many little events start stepping on one another. Here I was particularly impressed by the way the main vocalist was presented with the Super Ground Cube on; the voice was denser, more specific and more here. I’d already noticed that vocal-related quality on every track up to this point, but on “Breezeblocks” it was particularly apparent. I also think that the plainly better-presented vocal jobs were only part of the story. The entire landscape felt, there’s that word again, three-dimensional; enveloping, breathing and simply put, present in my room. For simplicity’s sake, let’s say that without today’s arrival my system, already ace in all image-related departments, sounded a bit flatter by comparison. After several hours, that difference became hard to ignore.Värttinä’s “Linnunmieli,” from Ilmatar, is an energetic piece of contemporary Finnish/Karelian folk built around tightly interlocked percussion, accordion, strings and the band’s distinctive female vocal harmonies. The arrangement is busy but highly rhythmic, with a strong sense of forward motion and plenty of small instrumental details flying around the vocals. Its combination of earthy acoustic timbres, brisk rhythmic accents and layered voices makes it particularly revealing when listening for clarity, separation, transient snap and the ability to keep a complex musical picture organised. I listen to this track particularly to map how its space is affected by various hardware sent my way; how distinct is the introductory female vocal to the right, how layered is the space behind, how substantial is the accompanying drum behind the key images, and so forth. I also can’t listen to “Linnunmieli” too loud, as it becomes too piercing for my taste. The Super Ground Cube changed that, allowing me to ramp up the volume by several notches without being penalised for it. All female singers remained perfectly intelligible, more colourful and fuller than before, but that shouty demeanour, particularly during the chorus parts, was tamed to a meaningful extent. The song remained in its sunny and happy element, but the underlying calmness the Super Ground Cube brought to the table noticeably alleviated the fundamental issues I had with it. No, this didn’t turn it into a fabulously produced recording. It wasn’t that. The polishing job, however, and the way spatial depth and instrumental outlines in the background were portrayed, improved substantially.

The above examples are just a few among many that revealed the Super Ground Cube’s main fortes. With it on duty, the entire musical landscape simply felt more liberated, orderly and moist, with all the key shapes presented in a fleshier and more explicit fashion. That the outcome wasn’t any brighter, pointier or more incisive was one thing; the combination of this with sensibly higher stopping power over the bass resulted in a particular kind of ease that remained present regardless of whatever fare was currently on the menu. Let me stress that the way the Super Ground Cube’s input was heard on “Trøllabundin,” say, was something even a hardcore naysayer would have difficulty denying. Ten seconds were all it took to form a firm notion of how differently the air in my listening room propagated, how much less wobble there was, and how much more focused the track’s foundational bass line was. All this, combined with the product’s ability to portray key vocal lines with far greater specificity, nuance, finesse, and textural density, is why I think ace communication is today’s specialty. The header title merely points that out.As packed with various potent resonance-control footers, noise-rejecting cables and brilliant Firewall filters installed in many places as it already is, my system is excellent on that comms front. The Super Ground Cube, meanwhile, simply revealed how much better that particular aspect can get when a proper grounding box is added on top of all the accessories that my carefully curated platform already accommodates.  Knowing this, I had to take the Super Ground Cube to my nearfield setup, which doesn’t have any fancy stuff in it. It comprises just a pair of Boenicke W5 monitors hooked to a long-discontinued NuForce STA-200 stereo power amp, fronted by iFi audio’s ZEN DAC V2, which connects to my dual-screen PC setup via USB. In that unconditioned environment, the Super Ground Cube’s input felt every bit as present as in my main system, if not more. Nearfield isn’t ideal for the W5s, as these really need ample space around them to work at their very best. Today’s subject didn’t change that, nor could it. It did, however, remove a lot of shakiness from the view and flaunt its other traits as explained above. Yes, adding a roughly €5’000 grounding cube to that setup made little financial sense. No matter. The point of the exercise was elsewhere: the Super Ground Cube replicated its behaviour in two very different systems and use-case scenarios, suggesting that its input isn’t dependent on an already highly optimised setup. In other words, this box proved system-agnostic.

Lastly, the two remaining matters left to discuss revolve around the Super Ground Cube’s potency and its behaviour depending on the switch setting. The former is straightforward. The product does a lot, in the sense that playback quality with it feels much better than without, period. While that difference isn’t in the realm of, say, switching from one speaker set to another, it is clearly there, and on many tracks demonstrable enough to appreciate within mere seconds of listening. This difference, however, doesn’t involve any tonal-balance alterations; it’s simply not that sort of action. If anything, the polishing procedure that the Super Ground Cube offers relates to the atmosphere, control, easefulness, fluency, flow, and prettiness of what we hear and experience. This is why I imagine that listeners unfamiliar with audiophile lingo would have a hard time describing the before-and-after delta. Many would notice that the overall listening experience had changed in a way that feels clearly superior, just difficult to put into words.The second subject—the switch settings—is a more complex and subtle matter. The difference in their impact on my system was sensible, but mild. The middle position indeed produced the leanest and most open outcome, the low setting added some extra mass, as per the manufacturer’s description, while the uppermost option felt as if it sat somewhere in between the two. Since I’m a sucker for spatial liberation, the middle setting was the one that had me sold. The way I see it, even if the Super Ground Cube had no switches to play with, I’d still consider it an impressive accessory, no less. Let’s wrap.

While I may sound like a broken record by now, the Stein Music Super Ground Cube belongs to that rather peculiar corner of high-end audio populated by people who already have the expensive stuff sorted, their key components firmly in place, and an army of various tweaks deployed around them, yet still aren’t quite ready to call it a day. For such folks, a standalone grounding solution may be the next logical rabbit hole to disappear into. That’s a niche clientele, no question about it. The Cube’s basic looks, steep asking price and complete lack of bragging rights in front of audiophile friends don’t exactly help its case either. This is no eye candy that will make your system look more expensive, and there isn’t much to explain when someone asks what it does. In practice, however, it does a lot, and those who already know what this kind of product can contribute, well, they know. For everyone else, hopefully this rather lengthy story has provided a useful data point and perhaps enough food for thought to give grounding hardware a fair shake. Besides, this is a one-time expense that, due to its MO, should easily outlive loudspeaker, source and amplifier rotations to come. In high-end audio, where boxes come and go left, right and center, something as universal as Holger Stein’s grounding effort isn’t a bad thing to have around.

Associated equipment:

Retail prices of reviewed components in EU (incl. VAT):

  • Stein Music Super Ground Cube : €4’800

 

Manufacturer: Stein Music

 

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