Note: for the full suite of measurements from the SoundStage! Audio-Electronics Lab, click here.

Ferrum Audio CEO Marcin Hamerla is evidently fond of wordplay. The Wandla DAC gets its name from Wandler, a word meaning “converter” in German—a language Hamerla speaks in addition to English and his native Polish. The Hypsos power supply is likewise cleverly named, drawing its moniker dually from the Grecian term for the sublime and from the device’s function as a hybrid power-supply system. The company’s name is inspired by the large deposits of iron ore found near its headquarters on the outskirts of Warsaw, Poland. But these are just words. What’s in a name, after all?


Ferrum is still a young company, just three years old as I write this, and yet has already built quite a reputation for itself. The $1195 Hypsos power supply (all prices in USD, though note that all Ferrum products have the same price in EUR as USD) and $1995 Oor headphone amp both have won EISA awards in their respective categories. And the Wandla DAC, at $2795, is the company’s flagship offering, having met with similar acclaim since its introduction midway through 2023—and, of course, another EISA victory. Words are cheap, but Ferrum clearly isn’t content simply to mumble; this company is doing something. Keen to find out exactly what, I made Hamerla promise to send me both a Wandla and a Hypsos shortly after meeting him at Audio Video Show 2023 in Warsaw last October.


The Wandla and the Hypsos each occupy a chassis that measures 2″H × 8.6″W × 8.1″D, not including feet, connectors, or knobs. Rust-colored slabs of lacquered weathering steel, with inset illuminated Ferrum logos, form the left of the devices’ fasciae, while a black knob occupies their right side. Each has an LCD screen on its front, though the Wandla’s is bigger and has capacitive-touch capabilities, which the Hypsos’s screen lacks. Things get more dissimilar around back, where the Wandla has a bevy of connectors for inputs and outputs; on the Hypsos, there are just four.

Hypsos power supply technical description

A standard IEC power-cord inlet with an integrated fuse drawer and power switch and a four-pin locking DC output connector occupy the back of the Hypsos. Why four pins for DC? More on that in a sec. There’s also a 3.5mm jack for use with a 12V trigger (the Hypsos can either trigger or be triggered by another device) and a Micro-USB jack that allows for future firmware upgrades. Setting the device’s output voltage, screen brightness, and so on is all done using the knob on the right. The Hypsos’s home screen displays the nominal voltage that the powered device expects, the actual output voltage, output power, and output current.


Most audiophiles understand that clean DC power is crucial for getting the best sound quality, but less understood is the importance of tight voltage regulation and fast current delivery. The Hypsos deals with these problems by using Kelvin connections when powering a component via its Ferrum Power Link cable. This is why there are four power pins instead of two: two connections transmit DC power, while the other two sense that power from within the component, forming a feedback loop that allows the Hypsos to regulate its power exactly as needed. This, Ferrum claims, is what makes the Hypsos superior to other power supplies when used with the Wandla. The heavy toroidal transformer, high-speed switching supply at the input, and low-noise linear regulator at the output allow the Hypsos to efficiently output voltages ranging from 5V to 30V.


The Hypsos comes preloaded with a lengthy list of compatible devices it can power, so it already knows the acceptable voltage range of whatever it’s powering. The Wandla, for example, has a nominal input of 24V but can be run anywhere from 22V to 30V. Within this range, the Hypsos’s output can be adjusted in 0.1V steps. Ferrum calls this “Sweet Spot Tuning,” or SST. Oh, your DAC, streamer, or phono preamp isn’t on the list? No biggie; the Hypsos has a manual mode that includes SST adjustments within a ±5% range. The heavy-duty supply has 80W on tap, so it can comfortably power two devices at once using a Ferrum Power Splitter ($249).

Wandla DAC technical description

The Wandla is built around the Serce (Polish for “heart”) board manufactured by HEM, Ferrum’s parent company. The Serce board was designed by HEM for use by OEMs as an all-in-one solution for digital audio. Ferrum says the Serce’s ARM chip performs the functions of five chips, working as a digital receiver for PCM and DSD data streams, enabling digital filters, doing MQA decoding and rendering, and enabling usability functions like the touchscreen, remote control, and input sensing. This explains the Wandla’s busy back panel—it accepts PCM data up to 24-bit/192kHz via an AES/EBU-configured XLR jack, S/PDIF via optical or coaxial cable, and ARC via HDMI. The USB Type-C connector and I2S via an additional HDMI port accept data streams up to 32/768 PCM and DSD256. All inputs have DoP (DSD-over-PCM) capability as well.


The most important bits are the ones that are audible, though, and that starts with an ESS Sabre ES9038PRO DAC chip. Ferrum has put a great deal of R&D into optimizing this chip, and has developed a unique I/V converter stage for it that the company claims is largely responsible for the Wandla’s performance. The ESS DAC generates an output that exists as a tiny flow of current but with nearly no voltage component—no volume, basically. The necessary step of converting the DAC’s output current to a voltage is conventionally done using a single op amp. This works well, but Ferrum has developed a compound amplifier solution to deal with the relatively high output current of the ES9038. This method uses two op amps cascaded together with negative feedback wrapping around both of them. A high-speed chip is used for the input, and a high-power amp drives the heavy load of the feedback resistor. This may sound like a bunch of tech gobbledygook to you, but Ferrum says the Wandla ekes better performance out of the ES9038PRO, avoiding the typical “ESS Sabre sound” many ascribe to DACs built around such chips. A more detailed explanation is available on Ferrum’s website if you’re interested.

The Wandla features five user-selectable digital filters. Jussi Laako of Signalyst has adapted several of the HQPlayer digital filters for the Wandla, denoted by their “HQ” prefix. My review sample came with the HQ Gauss, HQ Apodizing, HQ Apodizing Minimum Phase, HQ Short, and ESS Linear Phase filters; the list may be different by the time you read this. That’s because Ferrum has democratized the Wandla’s filters, allowing users to vote on their favorites, and plans to replace the least popular filters via firmware updates. Maybe a great idea, maybe not, but it certainly is original.


Following the digital filter and I/V stage, the music signal takes a fully balanced path through the output stage. Dual-mono Muses resistor-ladder volume-control chips allow the Wandla to be used as a preamp, but this function may be bypassed if the Wandla is only to serve as a DAC. There is the option to use digital volume attenuation as well, though obviously only with digital sources. A pair of RCA jacks allow an analog source to be used with the Wandla; another pair of RCAs and a pair of XLRs allow single-ended and balanced outputs, respectively. The Wandla claims a THD spec of 0.00009%, an unweighted THD+N spec of -115dB, and an A-weighted dynamic range of 127dB.

System overview and setup

I first used the Wandla strictly as a DAC with my McIntosh MA6850 integrated amplifier (discontinued; $3500 when available). However, an Instagram post by Ferrum helpfully reminded me that the Wandla is designed to be a great preamp as well as a DAC, so for most of my time with it, I used the Wandla’s variable outputs via its RCA jacks with my First Watt F5 power amplifier (discontinued; $3000 when available). Digital sources included an Oppo BDP-105 universal disc player (discontinued; $1199 when available) and an LG C1 OLED smart TV streaming Spotify. The speakers used were my trusty Paul Carmody–designed Amiga towers, built from a Parts Express kit. Belden four-conductor cables with Switchcraft RCA connectors linked the Wandla with the power amp, and AmazonBasics 14-gauge OFC wires connected this to the speakers. A Tributaries Delta 75-ohm coax cable linked the Oppo with the Wandla, while a no-name HDMI cable linked to the LG screen. The setup process was simple, as the Wandla and Hypsos are both pretty plug-and-play, despite their various settings.


Use and sound

Before I say anything about the sound quality of the Wandla, let me first express that it is absolutely a joy to use. The build quality is stellar for its price, the touchscreen is responsive and easy to navigate, and the volume knob and remote, while both lightweight, feel nice in the hand. The Wandla can be set up to be triggered by a source, so simply turning on the Oppo or the TV turned on the DAC. And since I used the eARC HDMI port on the LG C1, the TV’s remote could control the Wandla’s volume too. I suppose by now many of these convenience features are to be expected, and you’re probably just thankful I’ve joined the rest of you in the 21st century. In any case, I found the Wandla fabulously easy and pleasant to use. Now, on to the good stuff.

The Wandla with its stock power supply

I first casually used the Wandla with its included laptop charger–style SMPS and the McIntosh MA6850 to get a grasp of its gestalt of sound. The Wandla was set up for use as a preamp with the First Watt F5 for more serious listening, with the 24V SMPS still in place at first. I quickly found the analog volume control to be far better than the digital attenuator in my system. Your mileage may vary with your gear, but I found the analog attenuator to sound airier and provide clearer and more realistic vocals. The digital solution was veiled and flatter by comparison. The filter options were less clear-cut; I could hardly tell any difference between them, but settled on the HQ Gauss filter for its slight edge in balancing correct tonality, soundstage depth, and image specificity. In any case, these filters really ought to be considered ultra-fine tuning.


I opened Spotify and cued up Everyone’s Crushed by experimental pop duo Water From Your Eyes (256kbps AAC, Matador Records / Spotify). It’s an album that’s at once an intriguing, challenging, and catchy listen. On songs like the title track and “Out There,” the Wandla rendered lead vocalist Rachel Brown’s deadpan vocals with not only accurate timbre, but also credible depth, focus, and fleshy-ness, giving that “in-the-room” quality I adore. The deep synth bass, frenetic granular sampling, and unusual sonic textures throughout Everyone’s Crushed provided ample opportunity to get the gist of the Wandla’s sonic qualities. The sound tends strongly toward the warmer side of the spectrum, with great body and very slightly rounded sharp edges, but without any actual loss of detail. The bass seemed tonally accurate, and highs were extended, but sweet. Perhaps most striking of all was how deep, airy, and precise the soundstage was.

This was odd—ESS Sabre DACs just don’t do this in my experience. The soundstage is supposed to be flatter; detail is supposed to precede warmth in all cases. So, what was going on? When I first heard Ferrum’s claims about the Wandla’s I/V stage I was skeptical, but apparently they’ve really hit on something here. Do just a couple of op-amp chips really make the difference?

Next, I switched to the coaxial input and spun the Cure’s Disintegration (CD, Elektra 9 60855-2), using the Oppo BDP-105 as a transport. The room sound and reverberation of the snare hits seemed to translate from the recording especially well, and the separation between sonic images was exemplary. Synths, tom-toms, and baritone guitars all were exactly in their place on “Fascination Street.” Robert Smith’s vocals sounded especially palpable and immediate on “Closedown,” despite the track’s generous amounts of reverb.


I changed gears musically, playing Trio Jeepy by Branford Marsalis (CD, Columbia CK 44199). The trio’s cover of “The Nearness of You” is one of my reference tracks, and with the Wandla in place, the woody croak of Milt “the Judge” Hinton’s bowed double bass and the snap of Jeff “Tain” Watts’s kit came across beautifully. But the sax takes center stage on this recording, and I noted its particularly 3D and airy quality, of the sort you’d expect from a system with tubes in it somewhere.

Adding the Hypsos

I added the Hypsos at this point, starting at the Wandla’s nominal 24V but eventually settling at 28.5V. Listening to Branford, the Judge, and Tain cover Ornette Coleman’s “Peace” revealed that the Hypsos had further refined instrument separation and airiness, especially with percussion instruments. Bass gained in impact a bit too. It was clear that adjusting the Hypsos’s voltage had an audible effect.


Altering the power-supply voltage provoked a change that could be most easily explained as a tweak to the tonal balance. A lower voltage led to a cooler, more precise sound, while a higher voltage upped the warmth factor. But this is an oversimplification. Changing the Hypsos’s output voltage is more like an auditory dolly-zoom: the subject remains focused more or less in the center, but the layering, perspective, and depth of field all change together in a way that is clearly relative, but not necessarily intuitive. Naturally, this could be perceived as “warmer” or “cooler” sound, but such an observation only scratches the surface. To wit: listening to “Nearness” again while swinging between 22V and 30V on the Hypsos changed the height, depth, and three-dimensionality of the musicians. Thus, the Hypsos is a useful tool for optimizing the Wandla’s sound signature to fit one’s system and preferences.

Comparison—a face-off between ESS Sabre DACs

The Oppo BDP-105 also has an ESS Sabre chip in it, though in this case it’s the earlier ES9028Q2M. Our own Roger Kanno reviewed it in 2013, when it was new. And as a matter of fact, its onboard digital attenuation allows it to be used as a preamp, much like the Wandla. So, I quickly swapped cables and played “It’s All in Vain,” the opener from Wet’s Don’t You (CD, Columbia 88875 16991 2). This track is one of my reference tracks for deep bass, but it is also good for testing how a component deals with spatial cues, and how it deals with the slight glare on the vocals, too. Compared with the Wandla–Hypsos combination, the Oppo’s treatment was notably leaner and more forward. With the BDP-105, massed vocals had greater clarity and separation, but less body and texture than through the Ferrum setup. The bass with the Oppo was crushingly deep and tight, outdoing the Ferrum DAC and power supply, but it did so at the expense of nuance. Overall, the sound from the Oppo was less coherent, less musical, and less enjoyable than that of the Wandla, despite having an edge in a few aspects.

Returning to “The Nearness of You” helped to solidify my thoughts. Playing the disc via the BDP-105, Marsalis’s sax was reedier, and the soundstage was more constrained and seemed to emanate more from the speakers than from the space around them. Compared to the Ferrum, it gave an impression of greater detail, but with less tonal contrast and saturation. Dynamic attacks seemed to come faster, but were overall more compressed. There are many factors at play, but I believe the difference in the subjective sound quality of the two largely has to do with the different implementations of the DAC chip and its I/V stage.

I’ll offer another locus of comparison, the RME ADI-2 DAC FS ($1299), which I reviewed last year. While I didn’t have the RME and Ferrum DACs here at the same time to compare head-to-head, I can point out that, though the less-expensive RME unit has more usability features like its DSP-based parametric EQ and built-in headphone amp, the Wandla’s build quality, convenience, and subjective sound quality make up for the difference in features and price. I found the two DACs similar in how solid and composed they sounded, but the Wandla’s deeper, more textured soundstage was simply more fun to listen to. And by the way, yes, the ADI-2 DAC FS is included on the Hypsos’s list of compatible devices.

The bottom line

The Ferrum Wandla boasts great build quality, has all the essential features to make using it a real pleasure, and sounds lovely, with great specs to boot. The usual warnings about system matching and personal preferences still apply, but I can give the Wandla a hearty recommendation. I think to do better would likely mean shopping for far more exotic and expensive devices.


The Hypsos, likewise, receives my general recommendation, but with one qualification, which I think actually illustrates just how well Ferrum’s done with both products. The Hypsos power supply makes an excellent companion to the Wandla DAC, but it isn’t absolutely necessary to enjoy the Wandla. However, the Hypsos represents an ideal upgrade path for the Wandla and is a uniquely good standalone power supply in its own right. So, it gets a thumbs-up from me as well. Just be aware that adding the $1195 cost of the Hypsos to the Wandla pushes things into a price bracket where very few compromises can be made. With the Wandla DAC and Hypsos power supply, Ferrum has shown that it hasn’t compromised.

. . . Matt Bonaccio

Note: for the full suite of measurements from the SoundStage! Audio-Electronics Lab, click here.

Associated Equipment

  • Speakers: DIY Paul Carmody Amiga, built from a Parts Express kit.
  • Integrated amplifier: McIntosh Laboratory MA6850.
  • Power amplifier: First Watt F5.
  • Transport: Oppo BDP-105.
  • Digital cables: Tributaries Delta 75-ohm coaxial; generic HDMI; Monster Cable optical cable.
  • Analog interconnects: Shielded four-conductor Belden cables with Switchcraft connectors.
  • Speaker cables: AmazonBasics 14AWG OFC speaker cables.
  • Television: LG C1 OLED display, 55″, directly wired via Cat 6e cable to router.
  • Internet router: Netgear R6080; Jameco 170245 Linear Regulated DC supply.

Ferrum Audio Wandla Digital-to-Analog Converter and Hypsos Power Supply
Price: Wandla, $2795; Hypsos, $1195.
Warranty: Three years, parts and labor.

Ferrum Audio
Al. Jerozolimskie 475
05-800 Pruszków
Phone: +48 22 823 72 38


US distributor:
VANA, Ltd.
66 Southern Blvd., Ste C
Nesconset, NY 11767
Phone: (631) 246 4412