Over a decade ago, the late John Sunier of Audiophile Audition called me with a hardware review offer for the original AURALiC Aries streamer. I was clueless as to what a streamer was or what it was supposed to do, John was unable to offer any explanation of its function to me, and I only had the most rudimentary beginnings of a computer audio setup in the works—I ultimately declined the review. But my streaming audio fortunes took a big step forward when I evaluated streamers from High Resolution Technologies and Sonore (the Rendu series) in the following years, which helped move me much closer to the streaming audio mainstream.
But then I got "the email" from Dalibor Kasac that turned my streaming audio world on its end. Dalibor is with Euphony Audio in Croatia; they're the creators of the Euphony Stylus operating system and the Summus/Endpoint streamer-server setup that's been the focal point of my streaming audio system for the last five years. He'd read my reviews in Positive Feedback, and apparently saw in me someone who might be willing to take a leap of faith to next-level streaming with his Euphony Stylus OS. He virtually dragged me screaming into high-resolution streaming audio, but since then, Euphony and Stylus have evolved into first-rank solutions for high-end streaming digital, including server and library management, effortless streaming, and most importantly, world-class music playback. It's an impressively sophisticated setup that has lifted me from the computer audio bush leagues to the streaming elite; you can read my original Euphony reviews HERE and HERE. Euphony also distributes a range of high-end audio equipment, and through them, I evaluated Germany's Naiu Laboratories Ella power amplifier. Its unique circuit topology has been effortlessly driving the loudspeakers in my digital source system for a couple of years and contributes mightily to the superb sonics of that system—you can read my review of the Naiu Ella amp HERE.
Exciting new developments at Euphony!
Dalibor and I often go months at a time without contact, followed by furious flurries of activity; that happened again in mid-2023 when he reached out to detail Euphony's experiences with a pair of affordable DACs from Topping. Including the E70 Velvet and the E30 II, which can each have their AKM chipsets configured for use as DSD-direct DACs. I acquired the $400 E70 Velvet and was astonished by how very good the sound was compared to my much more expensive Gustard DAC and clock combo, and I tag-teamed between the two for much of the following year.
Euphony upgraded my system to Stylus 4.0 in early 2024, which offered an improved GUI and more seamless functionality. Stylus 4.0 came with significant add-ons, like the availability of Mozzaik Upsampler and renewed Euphony support for Roon (I didn't initially delve into either subscription-based service)¹. In July, Dalibor let me know that a major Stylus OS upgrade, Release Candidate 24 (v20241022), would be available in late 2024, to be followed by the introduction of Euphony's new statement device, Streamverter, which is set to make its debut in early 2025. Streamverter will continue Euphony's proven approach of dual-computer streaming, but rather than separating server and streamer, it will house dual computer motherboards within a single chassis. From my viewpoint, simply eliminating the extraneous cabling that currently connects dual-PC Euphony installations will be a significant upgrade! Streamverter's operating system is highly customized for native digital file playback, and will contain a version of Mozzaik Upsampler that's capable of transcoding PCM files to DSD 128, which Dalibor is particularly excited about. Streamverter will represent the apex of Euphony's vision for digital music playback, and I'm totally stoked to eventually hear this new equipment in my own system!
In the meantime, Dalibor particularly wanted me to experience the DSD 64 version of Mozzaik Upsampler in advance of the eventual launch of Streamverter. And he also wanted me to know they were still testing moderately priced DACs, expanding their evaluation to include a pair from S.M.S.L., the D300 and the VMV D2R, along with the two previously mentioned Topping DACs. Which, by the way, they'd decided the $150 E30 II was the definite winner over the E70 Velvet; I quickly found one on Amazon, and in a couple of days it had taken the place of the E70 Velvet in my system. Dalibor then instructed me to do something that totally puzzled me: he had me disassemble my current digital streaming setup—including removing half the dual-PC Euphony setup I'd been enjoying for years!
When Euphony launched Stylus OS 4.0 in 2022, they also switched production of their current Summus and Endpoint units to include more robust AMD Ryzen processors in place of the Intel CPUs they'd been using². And having embraced Mozzaik Upsampler as part of their new reality, Euphony wanted to ensure that all existing and upcoming equipment could handle the demands of converting high bit-rate PCM to DSD 64 and eventually DSD 128. In order to guarantee that my current Intel-based Euphony installation would have the processing power to run the latest Stylus OS in combination with Mozzaik Upsampler, some changes to the Summus' BIOS might be necessary.
Moving backwards for improved performance?
The Euphony system that's maintained the status quo for several years here featured the dual-PC Summus/Endpoint setup, which is based around a pair of Intel NUC mini-computers running Euphony's highly customized version of Linux, both housed in custom Akasa cases. The Summus (4C) unit is the higher-powered (Intel Core i7) of the two, and is most often designated to provide the music server/library organizer/music player function. The Endpoint (2C) is slightly lower-powered (Intel Core i3) and predominantly functions in most setups as the streamer, so the lack of processing power isn't an issue. Euphony has always insisted that separating the streaming function to a second unit yields a stunning step up in sound quality, and that has definitely been my experience over the past few years.
I received another call from Dalibor to give me more background and to detail the changes that would take place. First of all, I needed to access the BIOS of the Euphony Summus device to confirm that Intel's Turbo Mode and Virtualization were both active (they were). At least temporarily, I'd remove the Euphony Endpoint and ditch the Gustard equipment, while utilizing only the Summus and E30 II DAC. Euphony's Robert Devcic remotely accessed my Summus to tweak the system settings and activate Mozzaik Upsampler. There was a method to the madness; with the current Stylus OS, the Euphony Endpoint couldn't handle the significantly larger and more heavily processed files created by Mozzaik, but the quad core Summus definitely could. Besides, the change to my system was only until the newest Stylus OS upgrade would be ready at the end of 2024. For an additional uptick in sound quality, Dalibor suggested I also order a USB battery from eBay ($25) to power the E30 II DAC; taking the DAC "off the grid" would afford it an increased level of transparency and effortlessness during playback. As usual, his assessment was spot-on!
How Mozzaik Upsampler transforms digital playback
The Mozzaik Upsampler plugin was created by Mozzaik Audio, another company based in Croatia that offers innovative hardware and software solutions for high-end audio. Mozzaik Upsampler converts all bit-and-sample rates of PCM to DSD 64 (SACD quality) for exclusive DSD playback through your DAC. Its lengthy development process avoided traditional digital filter models, creating a highly specialized DSD modulator that incorporates proprietary upsampling filters. Mozzaik's designers fine-tuned those filters by ear, and enlisted the assistance of listening panels during the tuning process. Euphony's Robert Devcic was an active participant in the listening panels, and was so impressed by what he heard, he secured licensing rights for the upsampler's use in the Stylus 4.0 release in 2022. Euphony has graciously granted me a subscription to Mozzaik Upsampler for evaluation in my system.
With almost two years of evaluation of Mozzaik Upsampler in their reference system and in the field, Robert and Dalibor are seriously impressed with its capabilities, but especially with its musicality. And it makes complete sense in a digital streaming environment to convert everything to DSD; manufacturers like PS Audio, for example, convert everything to DSD in their top-of-the-line Direct Stream DAC. Native DSD Music is offering albums that have been upconverted with a version HQ Player to levels as high as DSD 512; I have several of those DSD 512 albums and the sound quality is unbelievably good! With Mozzaik Upsampler in combination with the Topping E30 II set to direct-DSD mode, transcoded PCM files presented as DSD 64 sounded better than ever across my system!
Euphony Audio's High End Munich 2024 experience turbo-charged their approach to improved digital musicality
Euphony Audio shared a room at High End Munich 2024 with Canadian manufacturer Master Fidelity, who market a range of high-end digital audio equipment, most notably the NADAC D DAC and NADAC C master clock combo (MSRP of close to $60k for the pair). Both units were developed in cooperation with Merging Technologies, and they've quickly become industry standards and the go-to DAC and clock units for many professional recording studios. Including those of legendary producers Jim Anderson and Ulrike Schwarz of Anderson Audio New York, Morten Lindberg of 2L Music in Norway, and Bert van der Wolf of Northstar Recording Services and The Spirit of Turtle in the Netherlands. All of which utilize the highly acclaimed NADAC digital equipment in their award-winning studios.
The NADAC D digital-to-analog converter is considered the industry standard by many recording studios.
Dalibor was able to get the Master Fidelity NADAC DAC and clock combo for use in Euphony's evaluation system, and it quickly became their new reference for superior digital sound. Euphony used the NADAC system as they refined improvements to the Stylus OS, and they also compared the multiple affordable DACs on hand against the NADAC to determine if any might perform at a level that would satisfy not only themselves, but also their customers. After extensive testing, a clear winner emerged: the S.M.S.L. VMV D2R DAC. Which came within an eyelash of matching the reference sound quality of the NADAC system. Dalibor gushed about the sound of the VMV D2R in their reference system, where it offered "ninety percent" of the sound quality of the NADAC for a fraction of the price, and he strongly encouraged me to try and get my hands on one. Until that happened, I listened to the upsampled DSD 64 files thru the Topping E30 II with rapt attention—and was absolutely loving what I was hearing!
Upon switching Mozzaik Upsampler on, the gains with transcoded PCM files of every bit-and-sample rate was remarkable. I was shocked by how very good my CD-quality rips sounded when compared to the delta-sigma processed alternative, and I honestly felt that transcoded higher resolution PCM files were even better! Less compelling CD-quality rips from my library were presented with a greater sense of realism; there was a more pronounced stereo image, and analogous to my playback of native DSD files, the transcoded PCM playback sounded much more… analog in nature. Since the arrival of the Topping E30 II and Mozzaik Upsampler, I've been listening to a ton of rarely played CD rips, and the sound quality has been sooooo much better than on any previous system!
I was so enamored with what I was hearing from the Topping E30 II, I put acquiring a VMV D2R DAC on the back burner. But a September call from Dalibor got that back in motion; he was now ready for me to reinsert the Endpoint device back into the system, and Robert was ready to remote-in and fine-tune the system settings that would allow the dual-PC configuration to process the more demanding upsampled files. The following day I was heading out of town for about a week, so I fast-tracked my plan to get a VMV D2R as quickly as possible!
The S.M.S.L. VMV D2R DAC arrives with the help of APOS Audio
Figuring out how I'd get my hands on a VMV D2R posed a bit of a problem; I could find only one VMV D2R unit available in North America, and it was from an Amazon reseller I'd had an unpleasant experience with. I started rapidly making phone calls and sending out emails trying to find an alternate source. Amazingly, John Soriano of APOS Audio (S.M.S.L.'s North American distributor) was able to locate one for me at their California warehouse, where members of his team tracked one down. He then made the arrangements to have it sent via UPS 2nd-day air to my home outside of Charleston, South Carolina—thank you, John! The VMV D2R arrived, and upon my return, I inserted it into the system, set it for direct-DSD playback, then contacted Robert, who remotely adjusted the system settings.
It's easy to see what separates the S.M.S.L. VMV D2R from the pack of more affordable DACs. Its superb chipset from Japanese manufacturer ROHM Semiconductor—their flagship BD34301EKV DAC chip—is part of ROHM's MUS-IC™ series, and currently happens to be the most expensive individual DAC chip on the market. The BD34301EKV chip is designed for class-leading audio performance, and is even used by audio luminaries like Luxman in their flagship D-10X digital media player/DAC ($17k MSRP). Euphony's insistence on the ROHM chip's superiority and the VMV D2R's superb musicality spoke volumes to me, along with Dalibor's claims that the sound quality of the unit approached that of the uber-expensive Master Fidelity NADAC system. I was stoked to hear this in my own upgraded Summus/Endpoint streaming system.
With the Euphony streaming stack now reconfigured in my system, the VMV D2R DAC took the stage. The VMV D2R has advanced playback and connection options, with balanced outputs, additional digital inputs for i2S and AES EBU, MQA compatibility, and multiple options for 1-bit direct-DSD playback. The unit also features a built-in linear power supply with a British-made Porcupine toroidal transformer, and includes separate regulated power supplies for both digital and analog circuits. Dual high performance Accusilicon AS318 B clock units keep jitter non-existent, and it's capable of handling the highest bit-and-sample rates available for both PCM and DSD files. The display faceplate is made of tempered glass, and features a multi-function controller knob that can be used for both volume or function setup in the absence of the supplied remote, which is nicely made from a block of solid aluminum. The VMV D2R's specifications show it to be an impressively capable digital-to-analog converter, and my recent experience has proven it to be the finest DAC to ever occupy any of my systems.
A Mozzaik Upsampler glitch results in Euphony's Stylus 4.0 (RC 24) getting installed early!
I'm kind of a hypochondriac when playing digital music over the Euphony system; even if everything seems perfect, I'll often check the settings in Stylus to confirm that nothing sinister is going on. Something caught my attention not long after the VMV D2R DAC had been installed; I was listening to music with Mozzaik Upsampler engaged, and noticed that the CPU utilization seemed normal, but the quad core temps were approaching 100 degrees Centigrade. Switching off Mozzaik Upsampler restored everything back to a more normal temperature range. Numerous internet searches on Intel core temps revealed that when Turbo Mode was enabled in BIOS, the processor was designed to handle the higher temps, and no issues should arise from the temperature extremes as long as they remained within the specified range. But with the fanless Summus and Endpoint Akasa cases, I remained somewhat concerned about the high temps during Mozzaik playback. As it turned out in the last quarter of 2024, I'd been deeply involved in a multitude of LP reviews that were done using my all-analog source system, so I didn't put a ton of hours on the digital system, which was possibly a very lucky break!
Stylus 4.0 allows easy checks of baseline performance metrics like Core Temps and CPU/Memory utilitization.
I'd reached out to Robert about an unrelated issue, and at the last minute I mentioned the core temps problem, asking whether or not he thought I should be concerned. Robert very calmly told me that yes, he found the situation very concerning, but we could probably make a few adjustments to the Summus system settings to try and correct for it. But first of all, the new Stylus OS 4.0 Release Candidate 24 (v20241022) was now available, let's take some time to install it on both the Summus and Endpoint units, and then we'll address the core temps issue. Over a period of about three hours, both installations took place, then Robert went into the new Expert Settings field of the Summus and in an additional hour, was able to fine tune them. Such that when Mozzaik Upsampler was active, the system played perfectly and the temps only rose to a maximum of 65 degrees Centigrade (they're typically between 35 and 50 degrees in normal operation). While I'd basically convinced myself that everything was okay before Robert fixed this for me—thank God I opened my mouth and asked about it!
Information in the lower right of the screen confirms that Patricia Barber's Modern Cool is actually playing in DSD 512.
The Audio Output panel settings menu allows for DAC and Mozzaik Upsampling configuration.
Stylus 4.0 provides easy access to your streaming accounts, like my favorite, Qobuz.
Stylus 4.0's main menu allows for easy access to all aspects of the OS for both Summus and Endpoint devices.
Having been a Stylus user for years, the new OS (RC 24) is fairly marvelous; the new GUI is a modern work of digital art, and I'm constantly impressed by how very beautiful it is now compared to the relatively utilitarian appearance of the preceding version! It's more ergonomic and intuitive, and the new format makes the Stylus OS an absolute dream to use. And they actually fixed the one problem I had with Mozzaik Upsampler by adding a check box in the settings that allows the upsampler to ignore existing DSD files during playback. In its initial incarnation, when you selected "Upsample to DSD," it upsampled everything, including the 400+ DSD albums of every sample rate that exist on my music server. Having to constantly switch between Bit Perfect and Upsample to DSD wasn't a total pain, but not having to constantly switch between them is miraculous!
Euphony Audio's partnership with Bert van der Wolf and The Spirit of Turtle is a cornerstone of its digital philosophy
Dalibor has talked at length about his experiences with Mozzaik Upsampler and the astonishing job it does when upsampling DXD (PCM 24-bit/352.8kHz) to DSD. So much current music is being recorded in DXD—mainly because of its enhanced editing capabilities—but he argues passionately that DXD sounds so much more musical when upsampled to DSD. I'd had some past experience with high-resolution PCM; I reviewed Jim Anderson's 2021 recording of Patricia Barber's outstanding album Clique!, which was recorded in DXD. And high resolution digital files were supplied to me for evaluation, mainly because the album didn't exist in any physical format at the time. I felt the DXD files provided the finest digital sound quality I'd ever heard—bar none—and was convinced of the superiority of the medium based on my experiences with that one recording. And this came in spite of my having more than 400 DSD albums on my digital music server, and my being very vocal regarding the superiority of DSD as a transmission medium for high resolution audio. Dalibor insisted to me that an A/B evaluation of the DXD and converted-to-DSD files would clearly show the improved musicality of DSD.
Euphony Audio has been partnering with recording engineer and record label head Bert van der Wolf of Northstar Recording Services and The Spirit of Turtle, the EU-based online digital platform where his ultimate resolution recordings are available. Bert was one of the pioneers in the creation of Direct Stream Digital (DSD), working with both Sony and Philips on the creation of the SACD format, as well as with high-end digital giant dCS and early DSD proponents Channel Classics and Native DSD Music. Like the other high-end recording studios I mentioned, Northstar Recording utilizes the NADAC devices throughout their sessions, where everything is initially recorded to DXD (24-bit/352.8kHz PCM). Recording with DXD allows for a significant level of ease in editing recordings, but Bert's long history of experiences with DSD has taught him that it's the preferred medium for ultimate sound quality during playback. And while his site offers recordings in just about every bit-and-sample rate of PCM and DSD, his preference always leans toward DSD playback.
Converted to DSD 64, James Gaffigan's Prokofiev Symphonies displayed the kind of dynamics that gave the impression of an actual symphony orchestra, live in my listening room!
After getting the VMV D2R set up in the system, I reached out to Bert van der Wolf to ask if he would kindly supply me with a few of his DXD files for use during the evaluation. He's located in the Netherlands, and even though it was around 3 am local time there when I sent the email, he responded immediately, offering me whatever I needed for the review. I picked out several DXD albums from his site, and replied that whatever he could send—whether it was only a single file from each album—would be incredibly helpful to my process. When I awoke the next morning, an email with a Dropbox link was there for seven complete DXD albums, including Prokofiev's Complete Symphonies (James Gaffigan with the Netherlands RSO), the Complete Symphonies of Robert Schumann (Jan Willem de Vriend with the Stavanger SO) and Vivaldi's Le Quattro Stagioni (Sigiswald Kuijken and La Petite Bande). Wow! I immediately fired off an email that gushed with my gratitude, then started slowly downloading the massive files—the Dropbox downloader recommended downloading one file at a time, as each of them measured close to 1GB(!) compressed for delivery. That's a lot of data, and thank goodness I have unlimited upload/downloads from my internet provider!
Jan Willem de Vriend's Schumann Symphonies were rendered by Mozzaik Upsampler with a level of musicality and realism that simply defied belief!
At least a third of my music collection is made up of classical albums of every sort, so listening to Bert van der Wolf's recordings wasn't at all foreign to me. I chose first to listen to a cross-section of them as they were recorded in 24-bit/352.8kHz DXD. Which meant that in the Stylus OS, the Mozzaik Upsampler was set to "Bit Perfect," such that no upsampling was taking place during playback, and the DXD files were presented as originally recorded. And I actually thought they sounded exceptionally good; the DXD files were dynamic, musical, and presented a superb aural capture of real musicians playing in a real space that was presented with a remarkable level of fidelity. Finding differences between the DXD originals and DSD conversions might prove to be a tougher assignment than I first expected!
Upsampled to DSD 64, Sigiswald Kuijken and La Petite Bande's offering of Vivaldi's Le Quattro Stagioni was the most perfectly nuanced performance of these classic works I've ever heard.
I constantly hear audiophiles refer to a "like night and day" listening experience with certain software, equipment, loudspeakers, etc—but I'm not generally one to express an immediate feeling of certain superiority based on initial evaluations. Pronouncements along those lines often grow from repeated listening experiences. But with the S.M.S.L. VMV D2R DAC now in my system, upon switching the Mozzaik software to "Upsampling Mozzaik DSD," the changes I heard were jaw dropping and immediate. I now could hear a much wider and deeper soundstage that expanded beyond, behind, and in front of my KLH new production Model Five loudspeakers; I could more easily identify instrument positions within the soundstage, and the overall realism of the recording's capture of the sound space was suddenly über believable. But more importantly, the DXD files converted to DSD 64 were imbued with an impressive new level of musicality that simply defied belief; the orchestral string tone gained a noticeable measure of sweetness, and the crescendos were more viscerally powerful and dynamic. If listening while blindfolded, I might have easily believed that I was actually sitting in the presence of a live orchestra. Those Patricia Barber DXD files that I considered so superb in my original evaluation have been transfigured by Mozzaik Upsampler, and the goodness I initially heard in them is now next-level in comparison. The playback I'm now hearing has a level of realism that has me lunging for the repeat button time and time again; it's the very best digital sound I've ever heard in this system!
In the past, I might have attributed hearing a difference like this to my level of impairment from whatever substance I happened to be indulging in at the time. Astonished, dumbfounded, or even gobsmacked don't come close to expressing my nearly complete level of disbelief as Mozzaik upsampled the DXD files to DSD. And the effect was easily repeatable—as I switched on the fly between the bit perfect and upsample modes in Stylus, the transformation between input and output was, well—transformational! I've been raving for months about my incredulity at how good upsampling from CD-quality PCM files to DSD has been, but I never would have believed that the very highest rate of PCM (DXD) would also yield results that are every bit as impressive.
Euphony just keeps getting better—and the best is yet to come!
This experience has been a complete eye-opener for me—I've been a firm believer for a couple of decades now in the superiority of DSD, and I've constantly been on the hunt for rare or elusive SACDs I can't live without in independent record stores as well as online. Now that I can convert PCM to DSD through a software option, I no longer feel the need to spend upwards of $100 or more for that ultra rare SACD on eBay or Discogs!
I took part online in a fairly vigorous ongoing discussion recently concerning Steely Dan's album Aja, which mostly centered around which digital version—whether CD or SACD—was the best sounding. I bought the new Acoustic Sounds SACD, which was disappointingly less than great when compared to my original Red Book CD. But my rip of the original CD played with Mozzaik Upsampler sounded waaaaay better than the SACD—better in every conceivable way, with less noise, improved clarity, and impressive dynamics. While I found the improvements I heard when upsampling Bert van der Wolf's DXD files to DSD almost unbelievable, I didn't expect improvements of a similar magnitude from a forty-year-old CD pressing like Aja, but there they were!
My glimpse of Euphony's future on my legacy equipment with Stylus OS 4.0 (RC 24) and Mozzaik Upsampler offers the best digital streaming playback I've ever experienced on this system, and possibly on any system. I can't even begin to imagine how impressive the performance of the new Streamverter OS and hardware will be. It's a brave new world, but a very exciting one! I've said this a thousand times over in the past five or so years, but all things from Euphony come very highly recommended!
Euphony Summus II (2C)
Retail: $2999.95 - Stylus OS License: $119/year for Summus, $77/year for Endpoint
Euphony Summus II (4C)
Retail: $3799.95 - Stylus OS License: $119/year for Summus, $77/year for Endpoint
Mozzaik Upsampler
License: Approx. $40/year
S.M.S.L. VMV D2R DAC
Retail: $999
Euphony Audio
Mozzaik Audio
Apos Audio
All images courtesy of Euphony Audio, Mozzaik Audio, Apos Audio, Master Fidelity, High End Munich, Northstar Recording, The Spirit of Turtle, and the author.
¹ Euphony moved to a subscription based service with the release of Stylus 4.0. Subscription-based streaming seems to be the way of things in the current age of digital audio, and why shouldn't Euphony get paid for providing the kind of value-added excellence that Stylus, Summus, and (soon) Streamverter provide?
² Intel had announced they were discontinuing the NUC series, so switching to AMD processors was the logical move for Euphony.
