Media Server Reviews

Is audio reviewing a futile pursuit? As much as we reviewers may strive, through subjective observation and objective measurement, to accurately describe how a component looks, sounds, and performs, we frequently find words and numbers inadequate to communicate the mysteries that abound in the transcendent realm of music. How can we fully share what we feel when a component allows us to experience, sometimes afresh, often in a new way, sounds that elicit joy, sorrow, terror, or more subtle emotions? How do we encapsulate in words and measurements the sonic equivalent of the wide-eyed wonder that shines through a baby's eyes as she discovers something new?

Such emotions—hence such questions—can arise when we move from one music server to another, or even between different software running on the same server. They are particularly intense in the case of this review of the Ideon Absolute Stream meta edition (2024) ($24,000) and its optional add-on, the Ideon Alpha Wave LAN Optimizer ($6900), considering that the review lacks measurements (footnote 1).

Even the need for a component like this—a dedicated music streamer-server that runs its own software—is controversial. Some people use an all-purpose computer, one intended to serve a variety of functions and filled with programs that run nonstop in the background—quite successfully. Some use such a computer with specialized software such as Roon or Audirvana. Some even insist, often on the basis of some theoretical commitment (rarely on the basis of careful auditions), that all digital sources sound the same and that those of us who insist otherwise (on the basis of careful auditions) are fooling ourselves.

Somewhere out there a reader is thinking, "Serinus is treading on quicksand. All he needs to do to ensure that he never makes it through this review alive is to mention MQA." Rest assured, a mention of MQA lies ahead (footnote 2). So if, soon after reading this, you receive notice of my demise and wish to honor my memory, in lieu of flowers, please send a donation to the Society for the Prevention of Cruelty to MQA Lovers. Nonetheless, while I still live and without further hyperbole, I proceed.

The ideas behind Ideon
Nothing obvious and external greatly distinguishes the Ideon Absolute Stream meta edition (2024) from other dedicated music servers. Its cleanly designed front faceplate holds three items of importance: the company logo, an On/Off button, and a small blue LED that lights up after the On/Off button is depressed and the unit is ready to go (footnote 3). The back panel is similarly unremarkable, containing two "femto"-reclocked USB audio connections, one of which provides 5V; a LAN input; two USB ports for connecting external hard drives or USB sticks (or for audio input or output); company and model information; and a combination toggle switch/fuse holder/15A, three-pronged IEC input.

The Absolute Stream meta edition (2024) can render music files stored on its new, internal 4TB SSD (footnote 4) or on USB- or network-connected external storage. It can natively stream internet radio, Spotify, and Qobuz; native Qobuz integration is new. The meta edition also adds an embedded Roon core, allowing it to do everything any other Roon server can do. The 2024 meta edition boasts more memory than before—"new and faster enhanced memory"—and a "revamped, simplified interface for Ideon Audio's native playback software application" to deliver real-time "core" playback. More on that in a moment.

There's more going on under the proverbial hood. Ideon's website cites a "massively over-engineered power supply, abundant ultra-low noise power, discreet power lines to critical points of the circuit, circuit stability and isolation, constant phase/timing correction"; a CPU that's "highly prioritized for audio playback only, ensuring highly optimized sound quality"; a specially designed reclocking circuit that includes "no-compromise femto clock architecture embedded as standard" on an upgradable platform that eliminates jitter and provides "future-proof phase correction"; a "very large" main linear power bank composed of low-ESR (equivalent series resistance) silk capacitors and a hand-made, high-wattage audiophile transformer; "proprietary, upgradable, zero-noise rectification active bridging technology" to eliminate diode-rectification noise; four separate, discrete power lines with "ultra-low noise linear power ... providing the different voltage levels the device requires"; a "proprietary, ultra-low ESR bypass power filter" to improve transient current quality because "we discovered that the quality of transient current going to the CPU affected sound"; short signal paths without wiring; no switching power supplies; and the reduction of internal noise-inducing peripheral circuits "as much as possible." All this, which I managed to compress into a single, very long sentence, weighs 49lb and resides in a CNC-milled chassis that takes 15 hours to fabricate.

To gain further insight into the product, I Zoomed with Athens-based Ideon co-owner and CEO/software architect/product optimizer George Ligerakis, US distributor Audio Skies' Michael Vamos, and Ideon Network Engineer Emilios Ermidis. Language barriers prevented the participation of the chief designer and co-owner, electrical engineer Vassilis Tounas.

Ligerakis, whose degree in information management and mathematics led to work in the IT industry, software marketing management, and psychology, explained that Ideon has a group of eight people, including the longtime chief audio engineer for the local philharmonic and other members of the music industry, who join Ideon's team to evaluate the sonics of Ideon products. Multiple listening sessions transpire before everyone signs off on the final product's sound.

Vamos emphasized that Ideon uses a "very high-quality CPU optimized to only play music, with extremely low latency. ... It plays live with no other processes running in parallel. As far as we know, unlike any other streamer on the market, the Ideon CPU plays directly and live from the kernel without any processing or lag. Ideon also uses totally overpowered, very quiet linear power supplies to achieve optimal sound quality."

A bit more about that "directly and live from the kernel" bit. One thing that means is that the track is buffered and played from memory, but there's more to it than that. Apparently, the native Linux recently—within the last few years—added "real-time" capability. This functionality is intended for mission-critical applications in which a computer must respond promptly—without significant latency—to an external event. It's especially helpful when the computer interacts with some real-world device, like a car or a medical device. Emilios told me that as far as he knows, Ideon is the first hi-fi manufacturer to utilize this native Linux "real-time" capability. He emphasized the Absolute's use of Linux's own core, not a home-built substitute, ensuring, he said, more reliable, efficient operation.

"Our big goal was to create a device very similar to our Absolute DAC (footnote 5) that, first of all, is so musical, with sound so organic, that it makes you enjoy your music above everything else," Ligerakis said. "We strive to find the right balance between the power needed for the CPU to perform optimally and the noise it creates. Some other companies use high-end CPUs that require a lot of power, but their power requirements make them impossible to power with pure, ultralow-noise linear power supplies. You have to power three or four different parts of a streamer's circuit with different voltages, which is hard to do with linear power supplies, so they resort to switching power supplies and then use other techniques to remove the noise those switching power supplies create. It becomes very complicated and requires a big chassis with a lot of different circuits. It took us two years to design a streamer that only uses pure linear power."

The Absolute Stream meta edition uses nine extremely low noise, industrial-grade voltage regulators. It also employs noise-reducing active-bridging rectification accomplished with FETs rather than noise-inducing active diodes that switch on and off—an implementation borrowed from fighter plane technology.

The Absolute Stream offers numerous software choices: their own software (which during the review period had only one streaming option, Qobuz); Roon; and other players that use the UPnP protocol, including JRiver. As you might expect, Ideon prefers the sound of its own software. How can different software sound different, even when it's serving up the same digital data? By running quieter. "Ideon did a test with a downloaded track," Vamos said. "Their software's CPU was using around 5% of its total capacity to play it, but Roon required between 30% to 60% of CPU capacity to play the same track. That's because Roon is working continuously while playing, searching for every single version of the track, including cover versions and live versions." More CPU means more electronic noise. "Roon has all these processes running in the background that do not help the sound. If you play Qobuz without going through Roon, the sound quality goes up quite a bit."

And if you prefer Roon's convenience and information-rich environment? "As far as I know, Ideon's is the only streamer that powers the internal Roon core with an ultralow-noise, internal linear power supply (footnote 6). Usually when you have Roon inside, you need to power it with a switch-mode power supply. Ideon's solution gives you better quality and eliminates the need for an external Roon core. We play Qobuz directly from the kernel of the operating system. The whole device plays one song directly from RAM."

Ideon reclocks signals with "perfect phase" using its own software and chips designed in collaboration with the chip manufacturer. The only Chinese part in the server is one pushbutton; everything else is sourced from the US, Japan, France, and Germany and assembled in Greece.

Ligerakis said, "Ideon deploys a CPU in a very unique way. We have designed the Absolute Stream's associated boards and reclocking modules to work with the CPU differently than other companies. We go to every little point where there is noise and bypass it using high-grade capacitors that bypass the normal CPU capacitors.

"Where rectification normally induces noise, we use FET-based noise elimination technology, linear power supplies, and extremely low-noise regulators. It's a chain of things in which we supply the right power for a processor to operate. Our construction is modular so that if we come up with a better part or board, you can install it. Our software is also self-updating, which makes the server future-proof. If we find a better way to do things, you don't have to sell the Absolute Stream and start over."

In short, the Ideon streamer does what other high-end server/streamer manufacturers do, each in their own way and, importantly, not necessarily with equal success: sends a clean, optimally reclocked signal out to the DAC from an electronically quiet environment.

Enter the Alpha Wave
I first learned about the Ideon Alpha Wave at Munich High End 2024. Without the Alpha Wave, which is optional, the Absolute Stream meta edition (2024) accepts audio data via Ethernet. Ideon, however, considers USB less prone to noise. The Alpha Wave LAN optimizer takes in an Ethernet signal, converts it to USB, reclocks it, and outputs the music data over USB at a speed of up to 1GB. This data can be fed into the Absolute Streamer via one of the USB 3.0 ports normally used for external storage.

Among its other advantages, this approach makes a fancy network switch unnecessary. Vamos: "Ethernet switches are kind of a Band-Aid because they still output LAN, and LAN is the actual noise problem. Ideon gets rid of LAN noise by converting LAN to USB 3.0 which is cleaner with less noise and distortion. "It is not mandatory to use the Alpha Wave with our Absolute Stream, and we do not require customers to do so. The Alpha Wave is a separate, optional product, designed for all network audio configurations, that improves the sound of the Absolute Stream just as it would improve the sound of any similar streamer device. The Absolute Stream performs extremely well on its own, without the Alpha Wave."

By email, Ligerakis reinforced Vamos's commentary. "The Alpha Wave is designed to be used with any streamer on any LAN network. It will enhance the performance of any streamer. It functions like an external LAN card, replacing a streamer's internal LAN card with an efficient, reclocked version powered by an ultra-low noise linear power supply. Since we believe that USB signal transfer is superior to LAN, the Alpha Wave provides USB output" to any USB-equipped DAC.

After two weeks of listening to the Absolute Stream, I asked Ligerakis and Vamos if they could provide an Alpha Wave for the review. When the Alpha Wave arrived, I let it settle in before comparing the sound of the Absolute Stream + Alpha Wave to the sound of the Absolute Stream solo.

---

Footnote 1: Stereophile does not routinely measure servers and other digital-only devices. Why? Technical Editor John Atkinson explains: "My tests have shown that streamer digital outputs are bit perfect. I could examine the jitter and eye pattern with the S/PDIF and AES3 outputs, but all the streamers I have tested do well on this test. As long as the DAC's USB input operates in the isochronous asynchronous mode—and almost all do these days—there is no point in testing that output. And an Ethernet output is impossible to test without extremely expensive test gear." Apparently our measurements fail to capture changes that, although sometimes subtle, are quite easy to hear.

Footnote 2: Justifiably, some declared MQA dead after MQA Ltd. was liquidated and Tidal abandoned the format. But then Lenbrook, parent company of NAD, Bluesound, and PSB, bought MQA's residual assets and have announced plans, with HDTracks, to initiate a service that streams "a novel application of the AIRIA by MQA Lab codec." AIRIA is one of the trademarked technologies Lenbrook spun off from MQA. Rumors of MQA's death might be premature.

Footnote 3: It is unnecessary to leave the Absolute Stream fully powered up 24/7; it will perform optimally after an hour of playback. From standby, turn it on in front and run signal through it for an hour before commencing serious listening.

Footnote 4: An 8TB SSD is also available.

Footnote 5: Review forthcoming. Alex Halberstadt reviewed Ideon's Ayazi mk2 D/A processor and 3R Master Time Black Star USB clock in "August 2022.

Footnote 6: This is challenging because the power requirements are high, and power must be delivered quickly, with a low output impedance—which is harder with a linear power supply. Ideon, though, apparently is not alone in using linear power supplies with the Roon core. Innuos claims this, and there may be others still.