Lumin U2X

Lumin’s latest flagship network player promises a new level of performance, one that could earn it a place among the very best devices of its kind. It’s a twin brother of the flagship X2 network player, except for a built-in D/A Converter. Does Lumin U2X truly deliver flagship-level performance? Let’s find out.

Introduction

Although Lumin’s debut—at least that’s how it still feels to me—took place quite recently, over the past 13 years, the brand has become virtually synonymous with high-end network players and transports. The story of its origins has been told dozens, if not hundreds, of times, but for the benefit of new audiophiles, let’s briefly bring it up once more. The engineers behind Lumin became interested in developing their own file player when a method for ripping SACDs using a Sony game console was made public, allowing anyone to rip material from this type of physical carrier.The process allowed the extracted material to be saved as 1-bit DSD files. For those who today treat the availability of such files as a certainty, let me remind you that back then, no DSD files were available to the public. One could buy SACDs, listen to them using specialized players, but that was it. The aforementioned method was hardly legal, but people started to rip SACDs, and the DSD files became „available”, if you know what I mean. The first Lumin, simply named Lumin (later renamed to A1), was developed first and foremost with playback of such DSD files in mind, though it didn’t neglect the PCM format either.

It was not the first brand to develop audiophile file players, but it was among the pioneers. Its executives never hid the fact that they drew inspiration from the Scottish company Linn, which, though best known for its turntables, was (if I’m not mistaken) the first company to offer an audio file player aimed at audiophiles. The result of this inspiration is the distinctive cover found on Lumin devices, which protrudes from the rear beyond the outline of the chassis. Although the inspirations are obvious and the brand has never hidden them, throughout all these years since the introduction of the first device, a team of engineers, specialists in electronics, mechanics, networking, and software development, has continuously worked on expanding the company’s product lineup, continuously making their products better and better.

The development has focused on creating circuits that ultimately deliver superior sound quality, ensure optimal operating conditions (shielding, vibration isolation, etc.), as well as increasingly convenient, more intuitive operation and enhanced functionality. The latter is just as important a feature as all the others, because while 13 years ago Lumin devices were intended almost exclusively for playing files from local storage or a local network, today users also want to access numerous streaming services. And this should be just as easy as playing files from a drive connected directly to the device.Having a pretty good overview of most of the devices Lumin has released since the A1, I can say with confidence that this manufacturer has done—and continues to do—a great job. The app for controlling the device works flawlessly and is a pleasure to use. The players and transports themselves operate flawlessly as well; their functionality seems to satisfy every possible user’s need, and the software updates released from time to time (I never encountered any issues during an update, which is yet another important quality) further improve the performance and usability of Lumin devices, and sometimes expand their already impressive functionality.

I admit, that I look forward to getting to know every new Lumin product, eager to see what the company has managed to achieve with their new components in terms of sound quality and functionality. This time, I had a chance to assess the new flagship network transport, designated U2X. Let me share my findings and conclusions with you.

Design & Features

What eyes can see

The first experience – unboxing and connecting the U2X – felt very familiar, pleasantly so. As already stated, I’ve been a fan of this brand’s products for years, simply because one of their key features has always been high musicality—something I look for in every audio component. The tested unit arrived in its characteristic sturdy double box, perfectly secured for transport. Inside, I found the transport unit itself, as well as an external linear power supply (based on two large toroidal transformers) in a much smaller but equally attractive enclosure. This feature allows users to place it in a prominent spot instead of hiding it behind the rack. It’s a small „detail” but often overlooked by competitors.The U2X’s chassis shares its aesthetics with other Lumin’s higher-end models: not too large, sleek, with a thick, convex front panel and a top plate that extends beyond the rear edge of the housing. Lumin machines its enclosures from a solid block of aluminum using CNC machines, then finishes them to perfection. For some time now, the higher-end models (though this feature has recently been trickling down the lineup) have featured a unique finish that is smooth, very pleasant to the touch, and noticeably less prone to fingerprints, which is particularly important in the black color variant (silver is available as well). The design is intended to ensure maximum rigidity, isolation from unwanted vibrations, and shielding to provide optimal operating conditions for the electronic components inside. Two finish options are available—silver and black. The box also includes a cable with multi-pin connectors on both ends for connecting the transport and the power supply.

The front features a distinctive small monochrome display that shows a bunch of information; however, when sitting (usually) a few meters away from it, you won’t be able to read much of it. The manufacturer assumes that users will have full control using the company’s app installed on a mobile device—a smartphone or tablet. This is evidenced by the brand’s traditional lack of any controls on the body of the U2X. And since controlling the device and playback is executed on the screen you’re holding in your hand, you’ll read all information there instead of on the device’s display. So I wouldn’t be surprised if some users took advantage of the option available in the Lumin app to dim or completely turn off that display. Let me add that the manufacturer has placed an elegantly engraved logo beneath the display, and that’s where any decorative elements of this design end.On the rear panel, you will find a fairly large number of connectors and ports. In the right corner (viewed from the back) is the aforementioned power inlet, followed by as many as four digital outputs. Users get AES/EBU, BNC, coaxial SPDIF, and optical Toslink at their disposal. Such a wide selection (and I’ll mention a fifth output in a moment), especially when combined with the ability to convert signals to and from virtually any format and resolution (more on that shortly), means that this device is suitable for owners of virtually any digital-to-analog converter. You can choose your preferred connection to the DAC, and even if it’s an older device, using its SPDIF, optical, or BNC input, pairing it with the U2X won’t be a problem.

Next, there are three BNC connectors. One of them is an input (for an external clock), while the other two are clock outputs, allowing you to connect additional devices featuring compatible inputs and synchronize them using a common clock. I should mention that the U2X features two high-end, built-in clocks—a femto clock and a 10 MHz clock. The user selects between them in the manufacturer’s app, and as my listening tests showed, excellent sound results are achieved, especially with the latter. Optionally, you can try an external clock, which I had the opportunity to do, and you can find my opinion on its impact on the sound below.Next are two USB ports and two network ports—one classic RJ-45 and one optical SFP. Following that is the fifth digital output, specifically a dedicated USB port that supports maximum transport capabilities (DSD up to DSD512 and PCM up to 768 kHz). Next to it, there is a gold-plated ground terminal.

Software features

Lumin has been developing its app for years, and it has gradually become better and more user-friendly. Today, the Android version I’ve been using is highly intuitive. I won’t even attempt to describe its full functionality, as there are countless options for customizing the app and its display to suit individual needs. For most users, the most important features are:
– Supported playback from a local NAS or server
– Support for playback from virtually all music streaming services—Tidal (including TIDAL Max high-res FLAC), Qobuz, Amazon Music; according to the manufacturer, even better sound quality with Spotify Connect, more internet radio stations, plus Audirvāna certification, support for the Plex server, and support for the Polish JPlay app
– selection of active digital output
– MQA playback mode selection
– RoonReady functionality
– multiroom functionality
– clock selection (one of two built-in options, or an external clock)
– resampling – for both PCM and DSD, you can choose native playback, up/down-sampling, or conversion to an alternative format (DSD to PCM and vice versa); for PCM, you can additionally select the word length (native, 24, or 32 bits); this feature ensures that every PCM and DSD file will be played back regardless of the DAC’s capabilities (provided the appropriate settings are selected)
– and finally, although this is a device that supplies a signal to the DAC, it is equipped with digital volume control – an advanced Leedh Processing algorithm, which operates, according to the manufacturer, losslessly.

I should also mention that the Lumin app includes an option to automatically check for new firmware updates for your model. As soon as I connected the U2X to the network in my room, I received a notification. I clicked OK, and after a few minutes—following a completely hassle-free installation—I was able to start listening to the music with the latest firmware installed.

Sound Quality

Lumin U2X arrived at a time when my listening room was already hosting quite a few other outstanding components, such as the latest version of the excellent AudioForm M200 bookshelf speakers and the American Boulder set consisting of the 1110 line-level preamplifier and the 1163 stereo power amplifier. Additionally, since the U2X supports an external clock, I managed to borrow one from Nautilus in Warsaw (thank you!). It allowed me to test the U2X performance when paired with the Sforzato PMC-05EX, the Japanese brand’s top-of-the-line clock.I fed Lumin files from my NAS via DL Custom Audio Sapphire Ethernet cables and a network setup consisting of a Silent Angel Bonn N8 switch powered by the company’s Forester F1 linear power supply (and an optical network isolator). The U2X offers two wired network connections: alongside the traditional RJ-45, you’ll also find an optical SFP port on the rear panel. Since I didn’t have a router/switch with optical ports, I used an Ethernet connection during the test; however, as I’ve already noted, the entire switch is optically isolated from the home network. It’s worth noting that Lumin offers a device labeled L2, which is a combination of a NAS and a switch. Not only can you install drives inside it to store (and share) music files, but it also offers four network ports, two of which are SFPs. It can therefore be a great addition to either the U2X or the X2 player.

In this setup, I controlled the playback using Lumin’s Android app. I conducted a significant portion of the listening sessions in the setup I always use (out of convenience) whenever possible. It means that U2X served as the so-called endpoint for my custom Roon server (so the signal traveled from the latter to the former via my home network), and playback was controlled using the Roon app. In both setups, I sent the digital signal from the Lumin’s dedicated and “isolated” (according to the manufacturer) USB Audio output, using the top-of-the-line DL Custom Audio Akoya USB cable to feed the signal to the input of the LampizatOr Poseidon.

From there, via the Next Level Tech Ether balanced interconnect, the signal travelled to either the Circle Labs P300 or Boulder 1110 preamplifier, or directly to the input of the Circle Labs M200 or Boulder 1163 power amplifier. Whenever a second balanced connection was necessary, I used the KBL Sound Himalaya 2 XLR. Each amplifier, via WK Audio TheRAY Exclusive speaker cables (terminated with the spades required for use with the Boulder amplifier), drove either the aforementioned AudioForm M200 or the GrandiNote MACH4. Let’s finally get to the performance assessment of the Lumin U2X.One could argue whether file transport has its own sound, though the same could be said, for example, of a CD transport. After all, these are devices that read data from media (files or discs) and convert it into a signal that is acceptable to a digital-to-analog converter. So, strictly speaking, they don’t have a sound of their own, but the quality and precision of the signal delivery (including timing) that they provide to the DAC, as practical tests show, is of great importance to the ultimate sound quality. The Lumin U2X is the brand’s flagship network transport, so it incorporates everything its engineers have learned over more than a decade of developing successive devices. Therefore, I had high expectations for it.

I should also reiterate that the U2X offers the option to use three different clocks. The first on the list (in the control app where the selection is made) is the built-in Femto, the second is the built-in 10 MHz clock, and the third option is an external 10 MHz clock. I started my listening sessions with the Femto, then compared my impressions with the second internal clock, and finally connected a high-end external clock from the Japanese brand Sforzato to determine whether using one yields noticeable results.

I began this part of the text by noting that file transport (seemingly) shouldn’t have much impact on the sound coming from the speakers. However, the sound I heard from my system—with the new Lumin sending the signal to the LampizatOr—was not only excellent, but also… distinctly “Lumin-like,” so to speak. A characteristic feature of all devices from this brand that I have listened to is a certain “friendliness” of the sound. One could simply state that with Lumin, sound becomes particularly musical or natural, if you will, though if we were to explain the meaning of each of these terms, we would still arrive at a unique—and in this case, downright outstanding (!)—combination of coherence, fluidity, and richness.Interestingly, I always attributed these characteristics to both types of Lumin devices I tested, ones that featured the brand’s proprietary DACs (i.e., file players) and those without them (i.e., transports). This does not mean that all models of this brand sound the same, because that is not the case, as those who have dealt with several of their products surely realize. In my opinion, however, they all share certain common traits and, as a result, a somewhat similar sonic character. The differences boil down (to put it simply) to shifts in emphasis on certain qualities more than others, and the degree of refinement in the presentation, which, of course, is made up of several elements. Nevertheless, the result is sufficiently similar in character that one can confidently speak of a single, shared sound philosophy to which the brand’s engineers have remained faithful from the very beginning.

So, going back to my earlier point, I’ll say once again that from the very start of my listening sessions, it was clear to me that the Lumin U2X fits perfectly with its predecessors in this regard, because it still has that “Lumin” sound. The only thing is that after just the first few hours of listening (actually much sooner, but I wanted to be sure), I became convinced that, first of all, this was the best device from this brand that I had ever listened to (though I had not experienced X1 or X2 at home), and, secondly, most importantly, one of the best network transports in general that I have hosted at home so far.

The U2X offers an extremely refined sound (I’ll say it again—this is a simplification, but the tested device has to be partially credited for the sound you ultimately get). It’s well-organized, rich, yet open, spacious, resonant, and dynamic. This refinement comes, first and foremost, from the excellent resolution and the resulting wealth of information, including the finest details—often referred to as “plankton.” This very “plankton” plays a significant role in the naturalness of the sound because, after all, live sound is full of (unobtrusive but omnipresent) details and subtleties; it delights listeners with its timbre and texture, and even non-musical elements play their part in its authenticity. Only when all of these elements are combined do they create a natural, true, realistic sound. That is exactly how I would describe the performance of the Lumin U2X.

So when listening to well-produced concerts—such as those by Patricia Barber or Keith Jarrett—I heard not only everything happening on stage—every instrument with its timbre, texture, details of the leading edge, sustain, and decay; the vocals with their distinctive features; the murmurs; the tapping of a foot to the beat; fingers sliding across the strings, etc., but also what the microphones picked up from outside the stage. After all, the hall’s acoustics, the sounds coming from it—including the audience’s reactions and applause, which are expressions of emotions evoked by the music—are what largely build the concert atmosphere, drawing the listener in and engaging them.

My experience with Lumin was therefore exactly the way I like it—as close as possible to what I often experience at concerts (I emphasize the word “close,” because it is, after all, merely a playback of a recording, an approximation of the concert experience). Lumin U2X, together with LampizatOr, painted scene after scene before my eyes—smaller, larger, shallower, deeper, wider, narrower depending on the mix, yet always precisely localizing the phantom images, giving them size, shape, and mass, making it really easy for me to imagine the events—told only through sound and unfolding before me—when I closed my eyes.

Secondly, the presentation, as delivered with the U2X in the setup, is completely relaxed. This is due to the calmness, combined with perfect control of all aspects of the sound, achieved without over-refining every element or detail. Lumin’s top-of-the-line transport offers an absolutely effortless presentation—one that is complete, coherent, and as fluid as… live music. Everything here has a perfectly defined place and form; the timing is flawless, and, as a result, we get a presentation that is exceptional (especially, though not only, for a digital player) and, on the other hand, very natural in its fluidity and coherence.

That is precisely why this sound is so pleasant to listen to, and why even after 12 hours (and I’ve had a few such sessions, with short breaks, of course) there are no signs of fatigue. To be precise, the latter will depend largely on the rest of the system—the DAC receives from U2X an excellent source material, but what it does with it is another matter. The Poseidon took full advantage of this transport’s class to show itself at its best; I achieved the same result later with another excellent tube DAC, the Acuhorn Lusso.

Another key feature of this sound is its high energy level—something that most distinguishes live performance from even the best recordings. Some devices are better at preserving all the energy captured in the recording (which is always lower than that of a live event), while others actually exacerbate those losses. My Poseidon belongs to the former category, just like the Lumin U2X, so together they made an excellent pair. That’s why, for example, Antonio Forcione’s concert sounded absolutely superb. With the tested server, everything was spot on—the energy of every strike on the strings, every drum, or metal percussion element beat, their speed, decay, the spaciousness of the entire presentation, the vast amounts of air surrounding the musicians, the lively audience reactions, and so on.

Everything I’ve described so far was the result of listening sessions with the basic—I suppose you could call it that—built-in clock: the Femto. To tell the truth, it sounded so good that I forgot to check the other options for quite some time. When I finally remembered them and selected the second of the built-in clocks, the 10MHz, in the app, I quickly regretted not having done so sooner. I regretted it not because the Lumin sounded poor with the Femto, but because the 10MHz clock raised the bar even higher.

The sound opened up more with it, filled with the air even more tightly, giving the instruments even more breathing room, and gained (natural!) brilliance, became more colorful (through even higher clarity of presentation), and even more precise. And I’m not trying to exaggerate the magnitude of the changes here. Sometimes it’s necessary to draw readers’ attention to subtle changes, but in this case, I can’t imagine that switching the clock would go unnoticed, even by an inexperienced listener. The change is significant, absolutely positive, and makes you want to listen to music from the U2X even more, because it sounds even livelier and more natural. Although, of course, it was already great with the Femto clock.

What about the very expensive Sforzato external clock? This change brought yet another audible improvement, but it was incomparably smaller than the one I achieved by choosing the built-in 10M over the Femto. The Lumin’s built-in 10M clock is so good that even a high-end external clock—any of them, not just the Sforzato’s—will bring about only a minor change at most. For those seeking perfection and not concerned about cost, purchasing an additional clock to extract those (notional) few percentage points of quality will likely make sense. For most, however, the built-in (10M) will be absolutely sufficient and will provide excellent sound quality.Finally, I also swapped out the DAC from my Poseidon to the Acuhorn Lusso, which I was testing at the same time. This is also a Polish device, significantly cheaper than the LampizatOr, though similar to some of its models in that its output stage uses tubes (and you can use several different types of triodes, including 300B, 2A3, PX25, 45, or PX4). Its power supply is not tube-based, and its functionality is more limited, but I can already reveal (spoiler alert, as the review is pending) that it performs very, very well via USB. Changing the DAC allowed me to conclude that the Lumin U2X, first of all, is so good that the differences between the DACs were obvious. Secondly, both DACs paired with this source were able to perform even better than with my server, ultimately proving—or at this stage, simply confirming—just how excellent a network transport the tested device is.

Summary

Lumin’s flagship network transport, the U2X model, is a perfect testament to the results achieved through more than a decade of relentless work, the acquisition of knowledge and experience, and the accumulation of insights into how both major and minor, seemingly insignificant changes affect sound quality. The result is a device that is rightly referred to as a flagship. It is, in fact, Lumin’s pinnacle achievement to date, but also one of the best devices of its kind on the market. Its class will be particularly appreciated by owners of expensive DACs, especially those who value natural, smooth, coherent, yet highly dynamic and energetic sound—in short, similar to what they experience at concerts. After all, I used the U2X with the LampizatOr Poseidon, and, in addition to my own reference components, it also worked with a truly expensive set from Boulder. It is safe to say, then, that the Lumin U2X is a reference-class device, one of the very best of its kind I have encountered. Therefore, I can recommend it even for very expensive systems. Congratulations to the Lumin team – you did it again and improved upon the excellence of your previous models!

You can find the Polish version of the review HERE.

Price (when reviewed):

• LUMIN U2X:  47.990 PLN

Manufacturer: LUMIN

Polish Distributor: AUDIO ATELIER

Technical specifications (according to the manufacturer):

• Solid billet CNC chassis for maximum stiffness and isolation
• External power supply featuring solid billet CNC construction, dual toroids, and low-noise linear regulator
• Native DSD512 & PCM768 playback
• DSD256 upsampling option for all files; PCM 384kHz upsampling option for all files
• 10M Clock input and outputs
• New isolated USB audio output plus Optical, Coaxial RCA, Coaxial BNC & AES/EBU: PCM 44.1kHz–192kHz, 16–24-bit; DSD (DoP, DSD over PCM) 2.8MHz, 1-bit
• 3 USB ports, including a NEW dedicated isolated USB output
• Fibre Network provides complete isolation from network digital noise
• Dual-Network interface with built-in Network Switch
• Leedh Processing lossless volume control
• Supports: Qobuz Connect, KKBox, QQMusic, Audirvāna Certification, TIDAL Max high-res FLAC support, Plex server support, Roon, additional free FLAC Lossless Radio Stations, improved Spotify Connect sound quality, JPlay iOS app support, and more
• Supported Audio File Formats: DSD Lossless: DSF (DSD), DIFF (DSD), DoP (DSD); PCM Lossless: FLAC, Apple Lossless (ALAC), WAV, AIFF; Compressed (lossy) Audio: MP3, MQA
• Dimensions: Player: 350mm (W), 345mm (D), 60mm (H), PSU (solid aluminium chassis): 106mm (W), 334mm (D), 60mm (H)
• Weight: 8kg + 4kg

Associated equipment:

• Digital source:  a custom passive server with WIN10, Roon, Fidelizer Pro 7.10, JCAT NET XE, and JCAT USB XE cards with FERRUM HYPSOS Signature power supply, KECES P8 (mono) linear power supply for the server, JCAT USB Isolator
• D/A Converter: LampizatOr Poseidon + Ideon Audio 3R Master Time (USB signal regenerator)
• Analog front end: J.Sikora Standard MAX turntable, J.Sikora KV12 & J.Sikora KV12 MAX tonearms, AirTight PC-3, Audio Technica PTG33 Prestige & LE SON LS10 MKII cartridges, Grandinote Celio MK IV & ESE Lab Nibiru V 5 phono stages.
• Power amplifiers: GrandiNote Shinai, Circle Labs M200, Art Audio Symphony II (modified)
• Preamplifier: Circle Labs P300
• Loudspeakers: GrandiNote MACH4, Ubiq Audio Model ONE Duelund Edition.
• Interconnects: Bastanis Imperial RCA x2, Soyaton Benchmark RCA, Hijiri Million Kiwami RCA, Hijiri HCI-20 RCA, TelluriumQ Ultra Black RCA, KBL Sound Himalaya 2 XLR, NxLT Ether XLR, David Laboga Custom Audio AKOYA USB, David Laboga Custom Audio Digital Sound Wave Sapphire Ethernet
• Speaker cables: Soyaton Benchmark Mk2, WK Audio TheRAY Exclusive
• Power cables: DL Custom Audio 3D-S-AC Connect, LessLoss DFPC Signature, Gigawatt LC-3
• Power: Gigawatt PF-2 MK2 and Gigawatt PC-3 SE Evo+; a custom power line with Gigawatt LC-Y in-wall cable; Gigawatt G-044 Schuko and Furutech FT-SWS-D (R)
• Network: Silent Angel Bonn N8 + Silent Angel Forester F1 + optical LAN isolator
• Racks: Base VI, Rogoz Audio 3RP3/BBS
• Anti-vibration accessories: ROGOZ-AUDIO SMO40 and CPPB16 platforms and ROGOZ AUDIO BW40MKII feet, OMEX Symphony 3S, Franc Accessories Ceramic Disc Slim Feet and Wood Block Platform