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Innuos ZEN Mini MK3 w/ LPSU review

  • Not long ago, I reviewed the Nativ Vita – a powerhouse music server with large hi-res touch screen, support for over a dozen streaming services, and vast connectivity. Even more recently, our publisher spent some time with the Auralic Altair G1, which takes a somewhat different approach yet still arrives absolutely brimming with functionality. Streaming and file-based-playback capabilities have even found their way into our integrated amplifiers, as documented by Phil Wright’s Ayre EX-8 coverage. And despite vinyl enjoying something of a renaissance, and the compact disc still hanging around (more in certain regions than others), file-based playback is clearly in very high demand.

    Not all of these features are useful to all people. I know more than a few music lovers who are plenty technically inclined, and do enjoy a streaming service or two, yet have no use for Bluetooth, AirPlay, touchscreen controls, WiFi or headphone outputs. These folks want a more straight forward device to serve as a dedicated digital transport, collecting and organizing their music library and serving it up headlessly i.e. without a directly attached screen for black-box library management and music delivery.

    Innuos may have just the right solution in their ZEN Mini MK3 (US$1249/€999), the gateway to their ZEN range of server/streamers.

    The ZEN Mini MK3 is absolutely not a feature-light proposition. Rather, it focusses on delivering what I’ll call the “core” music server functionality, to the fullest and without too much additional complexity. But I realize one person’s “extras” maybe someone else’s “essential features”, thus each reader must judge for themselves whether their needs line up with what Innuos has to offer.

    So just what exactly does the Zen Mini MK3 do? It’s a streamlined music server which runs a custom audio-oriented operating system for exceptional sound quality and ease of use. It has a built-in drive for ripping CDs. It works as a Roon Core or Roon Endpoint, as well as supporting UPnP mode and even a Sonos mode for people invested in that ecosystem. It stores music on its internal drive but can also stream from a local network storage – whether that’s a dedicated NAS or just a network share on your PC/Mac/Linux machine. It also streams from Tidal, Qobuz, and Spotify, and can do internet radio stations too – some of which broadcast in lossless quality these days. All of this comes in a compact, fanless package that should be simple to integrate into most any system.

    The Zen Mini MK3 starts at US$1249 equipped with 1TB worth of onboard storage, with more storage (up to 8TB) available for an additional cost. Measuring just 8.4 inches wide, 9.5 inches deep, and under 3 inches tall, the smallest (and most Kallax-Fi friendly) Innuos server is not much larger than the other Mini. That’d be Apple’s Mac Mini, which for years was popular as a music server but significantly less so as of its 2018 refresh – blame a combination of stubborn USB audio issues plus a lack of aftermarket modding support. With the Apple and Innuos’ prices landing in the same ballpark, I’ve long felt a dedicated device such as the Zen Mini makes more sense than a tweaked Mac Mini; and from what I’ve read on various forums, it seems many folks are now arriving at that same conclusion.

    The jump from Zen Mini MK2 to MK3 brought a host of improvements. The most significant change is the switch from an off-the-shelf motherboard to a custom design, optimized for audio performance. That optimization extends to the Ethernet input and we also get a handy Ethernet output which serves as a passthrough for another network device for easy system integration. Gone are the vestigial computer ports from prior models, replaced by far more useful Toslink and coaxial digital outputs. There’s also an RCA analog out – yes, the Zen Mini MK3 has an integrated DAC onboard, which appears to be a first for Innuos. A subtly redesigned chassis houses floating storage and optical drives, reducing vibration and thus mitigating its negative sonic impact.

    Innuos didn’t specify the CPU model used in the ZEN Mini MK2, but my sources indicate it was an Intel J1900. The MK3 update brings a newer Intel N4200 into play, which is both faster and more efficient than the J1900 and offers a maximum thermal footprint of just 6 watts. RAM is also doubled from 2GB to 4GB — a number previously only seen in the full-sized ZEN models. That might not sound like much but, remember, Innuos units are streamlined purpose-built devices. In base form, power is supplied by an external power brick, but the MK3 permits upgrading by adding a matching external linear power supply (US$699).

    While it’s easy to think of devices like this from a hardware standpoint only, that really only covers part of the equation. Just as important for sound quality is the software side. The InnuOS software platform is as beginner-friendly as it gets. Simply point a web browser at and it will automatically find any ZEN devices on the same network. From there, we can rip CDs, manage the library, back it up to an external location or switch between several modes of operation: Roon Ready, Roon Core, UPnP and Squeezebox Server. Setup is simple enough but in the event of networking issues, the InnuOS system can be remotely accessed by Innuos’s technical support team. Once configured, the system is pretty much set-and-forget.

    Let’s discuss ripping, as it is definitely a strong point of this device. Users can choose between WAV and FLAC encoding (I use the latter) and the entire process can be automated if you desire. Simply insert a disc, wait roughly 5 minutes for the process to complete, then remove the disc and repeat. A second slower, quieter ripping mode is handy for archiving one disc whilst listening to one already ripped.

    Regular readers may recall my experience with the Nativ Vita and Nativ’s $599 add-on CD drive. In comparison, the Zen Mini MK3 rips faster and is slightly less noisy even in standard mode. For metadata, Innuos uses the same FreeDB and MusicBrainz databases as Nativ, but also adds Discogs and GD3 — an additional pair of options seems to make all the difference to metadata supply: I could not find a single disc that the Zen Mini didn’t perfectly identify. This included underground trance, obscure metal and punk outfits and small-time releases from speciality audiophile labels. Classical and opera buffs may eventually find something to complain about (those genres being notoriously difficult) but, so far, I have yet to find anything which causes the ZEN Mini MK3 to flinch.

    Users with existing libraries can import their collection via network transfer or direct USB drive attachment. Here, the InnuOS software proved slightly less successful at properly identifying my data. It wasn’t bad by any means but did occasionally seem confused by compilations, classical releases and more obscure artists. In this respect, InnuOS’ performance seems on par with other big players such as Auralic and Aurender – they each do a generally good job, but none are perfect. Obviously, this could partially be blamed on the provenance of the collection and its existing metadata. And for Roon users, this portion doesn’t apply – Roon does a superlative job of organizing my collection, and I did most of my evaluation using Roon.

    I’m continually reminded that transport quality is an important factor in a higher-end system. Any old disc spinner or computer can functionally accomplish the task, but that only puts the downstream DAC at a disadvantage. While most DACs these days contain at least some provision for jitter reduction, relatively few properly address incoming electrical noise or other contamination. Experience says that I hear better sound quality when providing the DAC with as clean and accurate a signal as possible. That’s the ZEN Mini MK3’s other intent: it is designed to maximize the performance of any directly-attached DAC.

    My evaluation setup varied as the months went by. The Innuos started out serving data to the excellent McIntosh MHA150, which in turn supplied the Gallo Strada 2 loudspeakers with 50 watts per channel of solid-state grunt – perfect for midfield listening in my modestly-sized room. All cabling was from Audio Art, with the exception of a Silver Reference USB leash from the (now defunct) Cabledyne brand. After sending my evaluation MHA150 back to McIntosh, I swapped in another versatile machine – the S3 DAC/headphone amplifier from Keces Audio. Lastly, I threw in my Pass Labs HPA-1 headphone amplifier and fed it from a rotating cast of DACs: Exogal Comet Plus, BMC UltraDAC, and my current affordable bang-for-buck champion, the Airist R-2R. Headphones used included the Meze Empyrean, Audeze LCD-Z4, Sony MDR-Z1R, Sennheiser HD6XX and Fostex TH-X00.

    My first impression of the Innuos box, heard through the McIntosh/Gallo setup, was that of a very spacious and open performer; a sort of “reach out and touch it” situation which, in my experience, remains primarily the domain of a really well-sorted system. To look at things from another angle, this is often the first casualty when a weak-link is introduced to the chain. And sure enough, by switching to a pedestrian laptop as USB source, the presentation felt flatter and drew player outlines with more obvious blur. The Strada 2 speakers did their best with dispersion width, but the sound lacked the Innuos clarity with layering, scale and image specificity. Clearly, the Zen Mini MK3 was letting the McIntosh perform to its best ability and outplays a consumer-grade computer, designed for a multitude of task, not just music playback.

    Switching to headphones (still powered by the McIntosh) continued the same trend of open, three-dimensional sound. The Meze Empyrean, in particular, was able to do that spooky “out-of-head” thing where sounds seem to originate from far outside the bounds of the headphone. Whether playing Mozart, Meshuggah or Mutemath, the openness of the presentation was very much the prominent feature.

    Other, more basic aspects of the sound signature were also excellent – incisive top end, beautiful, expressive midrange, convincing bass impact. These attributes obviously vary based on one’s chain of equipment, but the Innuos is certainly capable of unleashing them if the rest of the chain is on board. Yet I kept going back to the open, spacious aspect as being the most prominent character trait of the Zen Mini MK3.

    Swapping out the McIntosh for the more affordable Keces S3 DAC/headphone amp brought more of the same. While it didn’t quite have the same dynamic gusto as the larger MHA150, it wasn’t terribly far behind either. I noted just a bit of treble hardness this time around, which made itself more apparent with certain headphones than others. Still, that was far from a deal-breaker, and I continued to enjoy that lifelike three-dimensionality I’ve been raving about. For a simple yet superb 2-box system, this pair seems like an excellent choice for headphone users, and the S3’s US$1399 asking price is well proportioned to the US$1249 Zen Mini MK3.

    From there, changes came rather quickly. I rotated DACs in and out, monitoring through the incisive Pass Labs amplifier and ultra-revealing Audeze LCD-24 headphones. Opinions began to solidify. Regardless of DAC used, I felt USB was the most insightful connection choice by a small but noticeable margin. That amount varied from DAC to DAC, and in some cases, the coaxial trailed by mere inches, so it’s not as if coax is a terrible choice by any means. But I did later confirm with Innuos head-honcho Nuno Vitorino that USB is theoretically best from a hardware standpoint, so users should plan on trying that one first.

    In terms of sonic signature, it seems the Innuos “house sound” is centred around soundstage spaciousness and imaging precision. Compared to the Nativ Vita, the Zen Mini MK3 feels more open and airy, but also has less meat-on-the-bone. Not to say the Innuos is “thin” per se, just that tonal richness takes something of a back seat comparatively. Here, system matching becomes important, to say nothing of one’s general sonic priorities.

    For me, jazz and classical and various acoustic works tended to benefit most from having Innuos at the helm. It made the Vita feel somewhat closed-in, a bit dull and even “small” at times. Yet throwing on some Black Flag, Homeboy Sandman, or Crystal Castles, I preferred the Vita’s relatively thicker tonality and rhythmic drive. Since this sort of music makes up the bulk of my listening, the Nativ Vita would more often than not be the better fit for me; but that could just as easily be reversed for someone else. And certain music, such as the quirky electronica of Minotaur Shock or almost any 70’s era classic rock, could go either way – was I in the mood for a more solid, grounded presentation, or did I want it light, open, and airy? Both were certainly valid choices. Keep in mind the Nativ Vita starts at $1599 with no onboard storage and adds another $599 for the external disc drive – the $1249 Innuos has nothing to be ashamed of here.

    I’ve use a powerful Xeon-based machine as my Roon server. With 6 cores/12 threads and 64GB RAM, this thing can handle pretty much anything I throw at it – major DSD upsampling, headphone crossfeed and EQ, and as many zones as I want all playing at the same time. The ZEN Mini MK3 is comparatively primitive in terms of processing power, so I wasn’t sure how well it would handle these functions, or even how it would cope with a large music library. Remember that Roon recommends solid-state drives for database duty (even if the actual library itself lives elsewhere), and Innuos has a slower, spinning-platter drive onboard. Is the Zen Mini MK3 capable enough to offer a quality Roon experience?

    The answer is mostly yes. I loaded the internal drive with over 800GB worth of music, representing roughly two thousand albums in a mixture of CD quality, hi-res PCM, and DSD. Navigation felt snappy enough, with a barely noticeable bit of lag that I probably wouldn’t recognize if I wasn’t used to my powerful server. Clicking “play” did not result in the practically immediate playback that I’m used to, but neither was it intrusively slow – think (modern) CD player reaction times and you’ll be on the right track. Overall I found the experience perfectly acceptable with a library of this size, though I can’t say how doubling or quadrupling the music collection might impact things. Interestingly, browsing Qobuz (still within Roon, of course) didn’t feel much different at all compared to my powerful server. I suspect this is due to the latency of using their streaming catalog versus my own local storage.

    As for the more advanced features, the Zen Mini MK3 is capable of handling them up to a certain point. DSD64 and DSD128 upsampling are easily within reach, while DSD256 was mostly fine save for the occasional dropout. I suggest trying higher PCM rates instead, which are often overlooked but can sound excellent with certain DACs – the device has no problem upsampling to 384kHz and beyond. It had no trouble running the Audeze presets, and was happy with basic EQ functionality. I also played 3 different zones simultaneously and the system handled that without issue.

    The main limitation has to do with combining these functions all at once. If you wanted 3 zones, but also wanted complex EQ on some of them and DSD upsampling on others, you’d find the little Innuos quickly running out of steam. So let your specific usage be your guide on this front. Then again, Innuos supports Roon Endpoint mode if users ever outgrow its server capabilities.

    Circling back to the matching external linear power supply, you’ll note that it appears in most of the pictures featured here. That’s because once added, I dreaded going back to the standard switch-mode solution. Not because the Zen Mini MK3 sounds poor in stock form, but rather because the device takes a significant leap upwards with the LPSU in play.

    The Innuos combo stack brings more solidity and tonal lushness to the table. I still wouldn’t call it thick or warm in absolute terms, but it fleshed things out enough to where I no longer felt I was missing anything. And this took place without impacting the expansive soundstage presentation, which now felt more enveloping. This was an engaging, tactile experience which felt as much at home with the $1399 Keces S3 as it did with the $8,000 BMC/Pass Labs setup.

    Now, forced to choose between the Nativ Vita and the upgraded Zen Mini stack, the decision becomes much more difficult. The Innuos nails the spaciousness aspect whilst no longer losing ground on sonic density. The argument then shifts to cover art display, with the Vita’s integrated touchscreen, controls battling the Zen’s iPad-based remote, as well as various extra features like Bluetooth and support for more streaming services. Both devices make very compelling cases for themselves and I could live happily ever after with either.

    The Bonus
    Remember the ZEN Mini’s analog output? It’s a first for Innuos. My first impression of it was somewhat underwhelming. With the switch mode power supply, it brought to mind the analog output of the old Squeezebox Touch – pretty respectable inner detail and leading-edge reproduction, yet obviously lacking in acoustic mass. I found this perfectly acceptable on the US$299 Squeezebox Touch, but the ZEN Mini MK3 sells for four times the price. This function is useful for background music or for pairing with entry-level gear but it might introduce a qualitative bottleneck to more capable systems.

    Things took a drastic turn when returning the LPSU to the mix. Now, this was a sound I could enjoy even with more potent ancillary gear. The lower octaves took on a solidity they had previously lacked, digital glare was toned down significantly and I even caught glimpses of that open, spacious feeling which consistently appeared via the digital outputs. To revisit the Logitech analogy – this would be my blast-from-the-past Bolder Audio modded Squeezebox Touch with external Channel Islands linear power supply, needing no apologies for its sonic prowess.

    The takeaway? Running the Zen Mini MK3/LPSU combo without an external DAC actually becomes a reasonable proposition. Adding a budget device like the iFi iDAC2 ($349) or Parasound zDAC V.2 ($549) feels different but not necessarily better, whilst the Mytek Liberty ($999) adds subtle improvements which certainly aren’t night and day. The ZEN’s Texas Instruments PCM5102-based internal DAC is expressive and generally competent enough to hold most listeners over until they can afford a really serious DAC offering a clear upgrade, at which point the Innuos stack could still be quite useful as a zone source for another room. I would like to see Innuos add the onboard DAC to the next generation of full-size ZEN models. It really is impressive once decoupled from the Mini’s stock SMPS.

    If it wasn’t already obvious, the Innuos Zen Mini MK3 gets high marks when used in the proper context. I really do recommend the upgraded power supply if possible, though it’s nice that users on a budget can stagger the purchase. Whether used as a transport or via its analog outoput, the double-stack offers gratifying sound with a particularly strong sense of spaciousness – I can’t think of anything in this price class which can touch it in that regard. Factor in exceptional CD ripping and the surprisingly excellent Roon experience, and we end up with a rather compelling device which represents “trickle down” technology at its very finest.

    Further information: Innuos

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    Written by John Grandberg

    John Grandberg is a US-based audio journalist who has been immersed in the scene for over a decade. A recovering percussionist, he has a particular affinity for headphones and associated gear.

    Letters to the editor: Raal, LG, Sony, Soundmagic & more