Those who have looked meticulously at the images depicted in the HEM company visit report might have already spotted the third offspring of the Ferrum family after the Statement in Hifi Fidelity-winning HYPSOS power supply and the OOR headphone amplifier: a combination of headphone amplifier and converter named the ERCO. Now a series model made its way to Gröbenzell.

Also their third device enjoys the merits of the Ferrum team’s rather special model name assignment. After the Greek HYPSOS and the Dutch OOR, it’s now time for Esperanto: ERCO - pronounced "ertso" - stands for ore and thus not in connection with the product itelf, as is the case with the OOR, but with the brand name instead. The front view of the ERCO differs from that of the OOR in only two minor details: First, the input selector switch provides access to one unbalanced analog input only, but at the same time enables access to all the digital signals that are available at the USB, coaxial or optical S/PDIF inputs. On the other hand, there is a Pentaconn jack for the balanced signal in addition to the usual 6.3 millimeter headphone jack output here. On the OOR, a four-pin XLR jack takes charge of this - which seems more practical to me. For Ferrum's target group of the ERCO, however, the decision made for the connection type also to be found on many digital audio players and headphones intended for mobile use eventually seems to be the better one. In that respect, Ferrum is similarly future-oriented as with the USB input: The new USB-C variant is used here. It’s nice to see that they have thought of including a USB-A to USB-C cable, which is probably not very common at the moment.

Most of you may know that HEM, Ferrum's parent company, has in the past been responsible for both the manufacturing and a not inconsiderable part of the development of the Mytek components - the brand that has earned an excellent reputation mainly thanks to its digital/analog and analog/digital converters for professional and home applications. When HEM’s boss Marcin Hamerla announced a Ferrum headphone amplifier/converter combo some time ago, I spontaneously thought of a DAC with headphone output. But the ERCO is anything but that: Not only at first glance it looks like a headphone amplifier hosting an additional converter. In its development, Ferrum took the successful OOR as a starting point and looked for ways to integrate a digital section. Adopting the OOR's circuitry one-to-one quickly proved to be impossible for both space and cost reasons, as Marcin Hamerla revealed. In the end, his engineering team developed an integrated circuit-based output stage that provides slightly less power than the OOR's discrete design, but without seriously sacrificing its sonic benefits. The connectivity and the possibility to vary the sound according to one's own taste by means of different filters or upsampling, as it is the case with a Mytek Brooklyn DAC+, are not to be found in the ERCO: Its place is not in the studio, but near a computer on the desktop or in a home hi-fi system.

Even though the ERCO merely offers one RCA input, almost the entire signal processing is carried out in balanced mode: On the one hand, the incoming analog signal is balanced directly after the input jacks, on the other hand, the proven ESS-Sabre ES9028PRO DAC chip provides a balanced signal itself. Since HEM has had the very best experience with the ES9028Pro, they saw no reason to switch to the current chip series from ESS-Sabre. The ES9028Pro processes PCM with up to 32 bit and 384 kilohertz as well as DSD256. A rotary switch on the back of the device allows to activate the bypass mode. This, however, is only possible by means of a screwdriver to avoid an unintentional activation, as in bypass mode the full output voltage is applied to the RCA and XLR outputs, bypassing therefore the blue ALPS four-channel potentiometer. The headphone outputs on the contrary are not affected by the bypass mode. Thus, even in an audio system with a preamplifier, both the converter and headphone amplifier can be used comfortably without switching or reconnecting cables.

Like the OOR, also the ERCO's internal power supply with its low-noise switching regulators, sophisticated filtering and linear low-drop voltage regulators (LDO) with fast transient response is the technological heritage of the HYPSOS. Actually the ERCO features two DC inputs as well: a classic 2.5/5.5-millimeter DC jack plug and a four-pin WEIPU plug, the same as on the HYPSOS. For the second option, the ERCO comes with a special power link cable with four-pin WEIPU connectors on both sides. In case a normal cable is used, the "4-Terminal Sensing Design" (4TSD) feature in the HYPSOS measures the voltage directly at the cable output, while when using the FPL cable it measures the voltage on the ERCO's motherboard instead. This allows the HYPSOS to regulate the voltage for the converter/headphone amplifier even more precisely.

But first, the ERCO has to get by without an additional power supply and accumulate a good number of operating hours. It turned out that even with a media converter like the ADOT, a few hours of break-in time improve the sonic performance, and this effect, as to my experience, is particularly pronounced with a digital-to-analog converter. In order to be able to run the ERCO continuously for a few days without blocking the systems in the study or living room as a result, the ERCO has to make do with a fairly simple environment to begin with, a set-up which should nevertheless represent a rather typical application for it: It fetches its data from a MacBook Pro via the supplied USB-A-to-C cable. The laptop sources the music files from an external USB hard drive - a rather questionable solution in terms of sound - and prepares them for the converter using Audirvana Studio, while the SendyAudio Peacock - my current favorite headphone right after the Stealth from Dan Clark Audio, which has long since returned to its distributor - is connected via the jack socket.

After a little more than a day, curiosity wins out and I take a brief listen into the album Changing Places by the Tord Gustavson Trio: The subtly differentiated "Deep As Love" as well as "Graceful Touch" with its quiet intro on the drums had already thrilled me when perfomed by the OOR, and, if my memory does not deceive me, the ERCO reproduces both the transients and the inner dynamics in a similarly convincing manner. At this point, it’s already clear to me that the sound of the now third member of the Ferrum family also has that certain something that makes the OOR particularly special. Since the latter had already left my listening room last fall, I am of course not able to evaluate how close the ERCO comes to the OOR. However, both headphone amplifiers clearly share the same sonic genes: lovely!

After a few more days, a Mytek Brooklyn DAC+ finds its way back home from a colleague, which I then also connect to the Mac with an ordinary cable, after it having completed a warming-up phase of several hours as well: With the Mytek, minimally less air surrounds the instruments and the acoustic space seems a bit smaller. The ERCO performs simply a bit more fluent and beguiling: the music takes the center stage and displaces any thoughts about the technology - what has already been the case with the OOR. The Mytek, on the other hand, is rather triggering memories of the SPL Phonitor in its precise and sober way of playing.

In order to evaluate the influence of the HYPSOS on the ERCO's sonic performance, the latter moves to a more refined environment: It finds a new home in one of the Artesania equipment supports in the listening room and is supposed to source its data from the USB output of the Auralic Aries G2.1. However, this doesn’t work even after one or the other reboot attempt of the Aries. Should the ERCO's USB-C be the cause for this misbehaviour? I'll talk to Marcin Hamerla about the problem and keep you posted - although I'm sure that very few hifi enthusiasts will pair a high-grade streamer with a headphone amp/converter combo. In my system, nevertheless, this variant is simply very useful: This way the ERCO is fed with optimally prepared digital signals, while the HYPSOS is in close proximity. That's why I am not about to give up yet, and so I connect Aries and ERCO via S/PDIF by means of an Audioquest Wild. And this works right away. To test the function I choose Arild Andersen's album Mira and instead of relying on the already often mentioned title "Raijin" I start with "Bygone": Tommy Smith plays his tenor saxophone in a very melodious and mellifluous manner, without any sharpness or harshness. Paolo Vinaccia dabs the rhythm with cymbals and a reticently struck drum, and Arild Andersen lets his bass sing warmly, even somewhat buzzy. The trio seems to perform within a larger space: A lot of air surrounds the instruments. A real pleasure!

And the HYPSOS intensifies this enjoyment even more: The sonic imaging appears to be even more free and open, the one or other detail somewhat takes a step beyond the perception threshold, double bass and bass drum simply get closer to the point, but without sacrificing the intensive musical flow. ERCO, HYPSOS and the Peacock let you revel in euphony. However, this is by no means to say that you can't enjoy music via headphones in an extremely satisfied way without the optional power supply. To find out how the HYPSOS behaves when the ERCO is merely operating as a converter, it makes its way into the living room. I activate the Bypass mode, connect the balanced outputs of the ERCO to Einstein's The Preamp and the coaxial S/PDIF input to the corresponding output of the Aries Femto – and yes, you guessed it: the USB input of the ERCO is not recognized by the Femto either. Whether it's due to the coaxial connection type or not, I can't say, but I’ve already experienced Shostakovich's Symphony No. 15 in the living room in a more vibrant way. And the spatial imaging seems a bit limited as well. As a pure converter, the ERCO in conjunction with its standard switching power supply doesn’t convince me as part of my extremely high-resolution system that it has become over time. That all changes completely when the Ferrum converter is powered by the HYPSOS. The ERCO suddenly sounds like a DAC from a much higher price range. In this application, I would not want to do without the HYPSOS under any circumstances. With it, the ERCO endulges with a large, very realistic sounding image, gripping dynamics, a transparent performance with strong timbres, and details that are nicely integrated into the musical flow. If you want to use the ERCO as a converter in a high-quality system, you can't avoid investing in a HYPSOS. This combination then offers a highly customer-friendly price/sound ratio!

However, it remains to be seen how the ERCO sounds as a pure preamp. In order to get this done, I first play a few records on the Brinkmann Avance equipped with Breuer and Titan i, connected in unbalanced mode to a Keces Sphono assigned for equalization and preamplification, which for its part is wired to the Einstein preamp. Before starting this review, I had not heard any LPs in this system configuration in the living room, and I am surprised which impact the exchange of the matured Brinkmann Marconi, of which there is meanwhile a MKII version around, against the Einstein has brought especially in terms of spatiality. The Preamp really doesn't make it easy for the ERCO to compete, but the Ferrum immediately wins you over with its open and dynamic performance. Its spatial imaging is as well convincing, even if the Einstein – while retailing for a more than six times higher price - still suggests a minimally larger soundstage. And, even if the ERCO in conjunction with the HYPSOS would offer preamplification services alone, it could rightly be praised as a bargain. Especially when paired to the optional power supply, it shows off both as a very convincing D/A converter and a headphone amplifier, which doesn’t by no means intend to deny its sonic relationship to the excellent OOR: Undoubted, this is Ferrum’s third big thing!