Ferrum Audio OOR and HYPSOS Headphone Amplifier | REVIEW

ferrum audio, focal clear mg and ideon audio

Should I dive back into headphones for 2022? I’m thinking about it. Most of my headphone listening these days is confined to my laptop, an AudioQuest Cobalt, a couple of relatively modest headphones and a subscription to Qobuz and Roon. Before this gear arrived from Poland, this Ferrum Audio OOR headphone amplifier matched to the HYPSOS external power supply, I was content. I thought I could move on and concentrate on loudspeakers and listening rooms and leave the headphones to headphone peeps like Brian Hunter and Eric Franklin Shook.

I wasn’t prepared for the Ferrum Audio OOR when it arrived. I had originally agreed to review the Ferrum Audio HYPSOS power supply, which was designed to be a big power-supply-in-a-box for components that use a wall wart. There was only one problem—most of the components I’ve been reviewing lately already have an external power supply. In fact, it’s been a while since there was a wall wart plugged into the Audioquest Niagara 3000 power conditioner.

Anthony Chiarella and Roy Feldstein of Vana Ltd., the US importers and distributors of Ferrum Audio, had a simple solution—Ferrum has also released a headphone amplifier, the OOR, which was designed to work with the HYPSOS. Ferrum Audio sells the 1,995 OOR and the 1,195 HYPSOS separately, but you can also save a little money by buying them as a bundle for 3,190 and getting the Ferrum Power Link (FPL) cable for free. (I know I’m not distinguishing the currency here, but the prices are the same in both euros and USD.) “Combining OOR with HYPSOS even exceeds the sum of the parts and unleashes capacities unheard of in both devices,” it explains on the Ferrum website.

focal clear mg

That sounds more like a complete product, I thought, but I did have one problem. If the Ferrum Audio duo was this innovative, this much of a jump in headphone performance, I needed a serious pair of headphones. That’s when Vana Ltd. Hooked me up with something incredibly and equally special—the $1,490 Focal Clear MG headphones.

One more log to toss in the fire, but at one point early in the review process Grover Neville returned from the last CanJam in LA and raved about the Ferrum Audio HYPSOS and OOR and started asking me a bunch of questions about how much I liked it so far. I had the complete system, ready to go. No more excuses. I owe this to Grover.

ferrum audio oor and hypsos

Ferrum Audio HYPSOS

Ferrum Audio is a new division for the Polish manufacturer HEM, which also handles Mytek and Clarus. Ferrum started off with the HYPSOS hybrid (switching/linear) power supply, a compact yet solidly built unit that focused on optimizing the voltage for specific pieces of gear. This was the essence of the “HYPSOS revolution” that adjusting the voltage could be a new way to fine tune the sonic performance.

With the Ferrum Audio HYPSOS, all you need to know is the output voltage of the device you’re connecting. (The HYPSOS range is 5-30V.) The HYPSOS does have a list of device presets—you just scroll down the list on the screen, and you can also request a new device through Ferrum support. Using the manual configuration mode, you can choose the voltage yourself and even adjust on the fly for the best sound quality. (You’ll also be able to set polarity at this point.) But there is an important caveat: WRONG VOLTAGE LEVEL AND POLARITY WILL DESTROY YOUR DEVICE! That made me a little nervous at first, but if you’re using the OOR headphone amp as your device, you don’t have to worry ‘bout a thing.

The Ferrum Audio HYPSOS uses a 4T Sensing Design (4TSD) to deliver the precise amount of voltage:

“Ensuring the exact voltage level precisely at the point of the powered device DC input terminal – special cable design and feedback to ensure flat voltage at every moment. This technique eliminates the harmful effects of the cable’s resistance effectively improving transient response.”

hypsos and oor back panel

Ferrum Audio OOR

The Ferrum Audio OOR is a perfect cosmetic match with the HYPSOS. You can use the OOR as a stand-alone headphone amplifier, which I did, or you can connect to the HYPSOS with Ferrum Audio’s proprietary FPL cable. So you can buy the OOR for around two grand, and then when finances allow go for the $1200 HYPSOS. But if you buy the bundle, the FPL is included.

Here’s what makes the FPL so important to Ferrum Audio’s technology:

“Our proprietary Ferrum Power Link (FPL) cable is key in making the marriage of OOR with HYPSOS a happy one. Two wires delivering the power and two wires providing the feedback to ensure flat voltage at every moment. This eliminates the harmful effects of the cable’s resistance effectively improving transient response. The current delivery speed at the powered device’s input is significantly improved.”

The Ferrum Audio OOR is a truly balanced, discrete amplifier design that keeps the output transistors on all the time, which reduces distortion. The front panel is neat and useful, with knobs for RCA/XLR operation, gain and volume levels. Both the HYPSOS and the OOR are small enough to tuck out of the way. They are small but, as I discovered, they are mighty.

ferrum audio hypsos oor

Ferrum Audio Set-ups

I started off with a familiar yet simple rig for the Ferrum Audio gear. I simply hooked up my Unison Research CDE CD player to the OOR headphone amplifier, and I compared the sound with and without the Hypsos through the Focal Clear MGs. The second rig was a bit more complicated—tiny boxes had invaded my listening room and wires were going everywhere. But the results were something else.

If you’ve read my review of the Ideon Audio Ayazi Mk. 2 DAC with the 3R Master Time re-clocking platform, you’ll know I achieved spectacular results with the Ferrum Audio gear. We’re talking four small boxes, my laptops, the Focal Clear MGs—I suggest in the Ayazi review that a small equipment rack would be required just to keep the headphone rig intact and neat.

This was the system that captured my heart. I’ll let you in on a little secret—I’m not sure if I’ve really been AMAZED at the sound of most headphone rigs. I’ve heard nice ones, I’ve heard expensive ones, and sometimes I find a combo of headphones and headphone amp and associated cables that might convince me that I want to keep them around. But this rig? This one right here?


ferrum audio with unison research


Let’s get the obvious comparisons out of the way quickly. The OOR sounds fantastic on its own. It presents a sound that’s utterly focused on transparency, on clean, on deep deep deep into the recording. I’ve been spending some time noticing the way silences can often sound different from one another but let me elaborate.

When I was a kid watching TV on our old Zenith black-and-white set—my parents always claimed that color TVs were too unrealistic until we kids threatened to go on strike—I noticed that the three networks all “sounded” different. There was a distinct NBC sound, a distinct ABC sound and a distinct CBS sound. It probably came to the all the electronics used to broadcast a signal, but those differences I heard became more obvious during moments of silence. I could have been blindfolded and I could still tell you which channel we were watching.

I hear those same silences in different types of high-end audio. I know it can’t quite be silence if I can hear it, so it’s more of a presence, a level of pressure in the room. When I experimented with new grounding solutions from Nordost, Atlas Cables and AudioQuest, that was one type of silence. Listening to a component that has been voiced toward neutrality, one that has been designed to reduce mechanical vibrations and noise—like the Pass Labs XP-27 phono stage—well, that’s another type of silence.

(Here’s an interesting sidebar: both the XP-27 and the Brinkmann Edison mk. II phono stages are incredibly quiet, and yet I can still feel differences in those silences. I’m still trying to find the right words to describe these observations even though I have known about them for most of my life.)

Anyway, when I connected the HYPSOS to the OOR, I heard that same sort of shift in the background. A knob had been turned up somewhere, and the size of the soundstage spread and settled in every direction. The unique thing, of course, is that the soundstage had grown inside my head, which prompted a feeling of euphoria. It was like driving through a winding mountain road and then turning a corner where you can see everything for miles. I think they call that sensation “taking one’s breath away.”

The HYPSOS, quite simply, offered better silence. It was larger and cleaner, and it sounded like I had walked through a door into a much bigger room.

ferrum audio, ideon


I’m going to focus more on the second system described above, because this is where the real magic started. Nothing wrong with the first system, but it felt vaguely the same as listening to the OOR with and without the HYPSOS.

Also, this rig with the Ferrum Audio and the Ideon Audio Ayazi DAC and 3R Master Time and the Focal Clear MG headphones and the Qobuz…well, that first weekend with OOR and the HYPSOS was a lost weekend. I dove in and listened to every single album I ever loved, and sometimes it felt like a new album and that was exciting AF.

This was undeniable with the new Let It Be Super Deluxe that Ken Micallef recently covered. He had the LP box set, which I should probably buy, but there it was on Qobuz, the day after I loaded Ken’s piece into the publishing queue, and Ken’s article has already whetted my appetite for a Beatles’ album I never really liked.

I’ve told the story before, but I bought a white vinyl Apple pressing of Let It Be when I was a teenager. It was the first “rare” album I purchased on purpose, for the princely sum of $25. (This was probably 1978, so that’s probably like $23,500 in 2021 dollars.) This was back in the days when colored vinyl collector’s discs sounded like pure crap, with tons of surface grunge and noise.

Maybe that’s why I never loved Let It Be. Listening to Let It Be Deluxe through the Ferrum Audio OOR and HYPSOS turned out to be a unexpectedly emotional experience. First of all, I can remember straining to hear all of that fun banter between the songs. With Ferrum Audio, I could hear every word clearly, and I could even imagine where everyone was standing. But the real emotional connections were to the music, and I felt like I was listening to something for the first time. This poignant moment made me sad and happy and thrilled, but ultimately I had one recurring thought, over and over:

Yes, I really need to get back into headphones. It’s only been a couple of years, but the ante has been upped.

ferrum audio

Ferrum Audio Conclusions

One thing I have to get out of the way: I loved the Focal Clear MG headphones. As in, maybe I have a new favorite headphone. As in, maybe I should make some calls. They’re comfortable and smooth and rich and everything I want from a pair of cans. I was all set to go into more depth, but I found out that our very own Eric Franklin Shook is finishing up a review on them as I write this. I’ll leave it to him but yeah, big thumbs up for me.

As for the Ferrum Audio OOR and HYPSOS? It’s a strange feeling to listen to this rig sometimes, as if I’m Rip van Winkle and headphone performance has suddenly made a quantum leap. The Ferrum gear is, as I’ve mentioned, extraordinarily open and clean and transparent and silent in ways I don’t quite understand. Before I tell you that this is by far the best headphone amplifier rig I’ve ever heard, and it just might be, I have gravitated toward warmer, more tube-like rigs in the past. I still feel like I might hear some incredible tube headphone amplifier down the road that I might prefer, but who cares about such a hypothesis?

Right here, right now, the Ferrum Audio duo is one of those products you listen to and think, will this change everything? It’s that surprising, and that much fun. Reviewer’s Choice.


focal clear mg with ferrum and ideon