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A technical tour-de-force, and one of the most satisfying and polished units I've ever had the privilege of using.

A Review On: Resonessence Labs Concero HP

Resonessence Labs Concero HP

Rated # 35 in Amp/DACs
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Review Details:
Audio Quality
Design
Quality
Value
tomscy2000
Posted · Updated · 3289 Views · 7 Comments

Pros: Clear, massive sonic superiority over all other USB-powered DAC/amps; Solid, bulletproof chassis designed with precision and care; Responsive service

Cons: Be willing to cough up the bucks for a true premium experience; Chassis is fingerprint-prone; No way to visually differentiate between digital filters

This review was adapted and modified from my review originally written for CYMBACAVUM, based off a review sample that I promptly purchased because I was so impressed with it.

 

You may have heard of Resonessence Labs — this small company in Kelowna, British Columbia rose to the top of audiophiles’ wishlists in 2011 when they released the Invicta — a meticulously engineered ES9018-based DAC that blew peoples’ hats away. They managed to pull off this feat by understanding ESS chips inside and out; Mark Mallinson, head honcho at Resonessence Labs, was a former operations director at ESSTech, and whilst forming Resonessence managed to recruit several members of his former engineering team that help design the ESS Sabre DAC architecture. In addition, Resonessence remains close to ESSTech, both literally and figuratively, as they’re located in the same area as ESSTech’s Kelowna research & development lab, while Mark’s brother, Martin Mallinson, remains at ESSTech as VP of Research & Development and Chief Scientist.

 

Obviously, then, there’s no question that Resonessence Labs has the skill and pedigree to make world-class DAC products. Not content with merely making one single, top-of-the-line model, they managed to trickle down technology from the Invicta to the more modestly priced Concero. The original Concero was greatly lauded for its performance and pleasing sound, putting many in the DAC world on notice. Resonessence dared to do better with this summer’s launch of the upgraded Concero line — the line-out Concero HD and the all-in-one DAC and amplifier, the Concero HP.

 

Because of its close ties with ESSTech, Resonessence Labs managed to design the new models around the all-new ES9018-2M chip, a low power, two-channel chip based off the venerable ES9018 (used in scores of high-end, reference level D/A converters, including their own). From technical specifications, the ES9018-2M bests (by a considerable margin) the ES9023 of the older Concero, while allowing preservation of an USB-powered form factor, selectable digital filters, and jitter reduction code — putting it on par, in terms of SNR and THD, with the ES9016 (which was actually used as the DAC section for the headphone output of the original Invicta). The switch to the new chip also gave the Concero HD and HP the ability to readily decode DSD64/128, as well as PCM up to 24-bit, 352.8 kHz (the DXD specification). In terms of format support and bitrate, Resonessence Labs has it covered to the nines.

 

I took the Concero HP pretty much everywhere. Yes. Even to In-N-Out!

 

Exterior/Packaging

 

Unfortunately, my very first impression (the box) of Resonessence wasn’t the most favorable. Clad in the simplest black cardboard box with two foam inserts, the Concero HP arrived to zero fanfare, pomp, or circumstance. Even the instruction manual looked plain, as though it were typeset in Microsoft Word. I had to remind myself that Resonessence Labs was all about the sound and the engineering. They let their products stand for what they are, rather than glitzy packaging.

 

Actually seeing the Concero HP for the first time instantly allayed any of my superficial, elitist fears, however. The Concero enclosure is CNC par excellence. At the back of the HP, Resonessence proudly emblazons the Canadian maple leaf to great effect. “Fabrique au Canada” is the theme, as the enclosure of the Concero HP (and the entire Resonessence product lineup for that matter) is the subcontracted work of local enclosure developers and CNC millers (Imagination Machine Works and Inspired Precision Machining) that usually reserve their services for much larger projects. In fact, other than the actual design work and final assembly, which are performed in-house, all Resonessence products harness the talents of local specialty workshops — an admirable feat both practical and patriotic.

 

The chassis of the Concero HP is a matte black, precision affair. Bruce Wayne would be a proud owner of the Concero HP (well, he’d most likely have an Invicta or Mirus, but he’d perhaps gift the HP to Dick Grayson). Stark and chiseled, all Resonessence products possess quite a bit of familial resemblance. Sans the glowing ring, the rotary knob on the HP appears to be a scaled-down version of the one on the Invicta, and shares with its bigger brother the same beveled front corners that take the predictable regularity out of a pure rectangular shape. The HP also possesses, apart from the rotary knob and 6.3mm headphone output, the same outward dimensions as the Concero and Concero HD, but the HP and HD actually have reworked innards that allow Resonessence to place the new PCB (also made and assembled locally in British Columbia by a military-grade electronics supplier) in place. Keep in mind, however, that the overall industrial design isn’t necessarily going to win any Red Dot Design Awards.

 

It is, nevertheless, one of the most solid-feeling structures I’ve come across in all of audio, and I can imagine the same exact fit and finish applied to the much pricier Invicta or Mirus. Needless to say, the Concero series does not skimp on its exterior finish. The anodized aluminum enclosure feels akin to the plates lining CT scanner rooms, stolidly monolithic. Brush your fingers over the surface of an operational Concero HP, and feel your Pacinian corpuscles underneath the skin pick up on the subtle vibrations of the overbuilt power regulators (though I wouldn’t recommend caressing the unit too much; the satin/matte finish is a bit of a skin oil blotting pad). Everything about the manufacturing is computer-controlled and tightly-regulated, and thus doesn’t come cheap. A substantial amount of the final cost of the Concero HP definitely goes into the production of this exceptionally-crafted chassis. Of all the different audio products that I’ve seen, no other unit with a similar footprint comes close to the fit and finish that Resonessence Labs demands — this thing is built to last.

 

Technical Design of the Concero HP

 

As alluded to before, the Concero HP (and HD) use the brand new ES9018-2M chip from ESSTech. While devices from other brands equipped with the chip are slated to come down the product pipeline soon (such as the GEEK), the only other device currently to use such a chip is the BBK Vivo X3. Resonessence was by far the first company to take advantage of this new chip. Theoretically, the ES9018-2M performs very similarly to the ES9016 used in the first version of the headamp stage of the Invicta (which, as of this year, has since been upgraded to the ES9018), but operates within a smaller power envelope and is packaged into a smaller 28-QFN form factor. The Concero HP, then, should in principle come quite close to the performance of the original Invicta’s much-lauded headphone output in single-ended mode, just with the core technological base of the lower-priced Concero.

 

The Concero HP and HD are not just the Concero with a new chip dropped in, however. While the three products share the same jitter reduction techniques coded into the Cypress Semiconductor USB receiver and Xilinx Spartan-6 FPGA core, several critical items were completely reworked. The power supply is different. The clock multiplexing, previously soft-implemented on the FPGA in the original Concero, is now a discrete hardware design. And since they’re such proficient software coders, I can’t imagine Resonessence making such a change unless it were for palpable improvement of jitter reduction. The FPGA is now reserved for the jitter reduction techniques, as well as the excellent IIR (infinite impulse response) and apodizing upsampling (4x, from 44.1/48 kHz sources) digital filters (see the Resonessence Labs website’s explanation for technical details).

 

As the ES9018-2M lacks the integrated line driver of the ES9023 on the original Concero, a pair of AD8397 opamps feed the output stage: one for the actual amplification, and another as a noise reference. Resonessence engineers seem to favor this opamp for its superior current delivery as well as rail-to-rail voltage swing. At full scale, the Concero HP outputs 3.5 Vrms (translates to a conventional 2.5× gain factor and nearly a 10 volt swing, peak to peak). It also transmits clean, clear power — up to 270 mW into 32 Ω and a -100 dB noise floor. While the power specs aren’t world beating, they’re very adequate for even the thirstiest full-sized dynamic headphones. IEMs aren’t even a question.

 

As Resonessence tends to employ a uniform design philosophy from the top-down, the Invicta employs a similar design process in its headphone amplifier. However, to keep within the 500 mA current draw limits of USB 2.0 specifications, however, the Resonessence engineering team couldn’t completely emulate the design of the Invicta’s headamp in the Concero HP. Even so, they retained the excellent 32-bit digital volume control of the ESS architecture.

 

Since the device is USB powered, the Concero HP is obviously intended mainly for a USB data stream. However, there’s also a coaxial output, complete with jitter reduction, that allows you to daisy-chain the Concero HP to other DACs as an USB-to-S/PDIF bridge. Interestingly, it can also be reconfigured to become a coaxial input in lieu of USB (but the USB port still has to be plugged in directly to a 5V power source, via a wall wart or USB power supply). I didn’t bother to test these features, however, as: (1) I don’t believe a small device such as this was intended to be used with coaxial input especially if there’s an USB input, and (2) I don’t have any sources/transports that accept or output S/PDIF in such a manner anymore (yes, I’ve gone completely to USB).

 

Power management is one of the remarkable things about this unit — with all but the absolute most sensitive of IEMs, the Concero HP is dead silent. Zero hiss. Even at 0 dB attenuation. There is hardly any difference between plugging it straight from the USB port of my laptop and having it filtered through the excellent iUSBPower. It’s truly an impressive feat, and remember, this unit measures in at only ~16 cubic inches!

 

Startup and the Computer Interface

 

There’s no need to tweak USB latency settings (the reference Thesycon driver allows for different safety levels and packet sizes) and the included ASIO driver was completely lag-free in Foobar, suggesting of Resonessence’s optimization of the code. All previous ASIO drivers I’ve tried, whether they be Thesycon-derived or C-Media-derived, managed to lag playback and any visualization I tried to run, and while that might be a sign that I should upgrade my laptop, the RUSB ASIO driver worked pain free from the get-go.

 

Let’s not forget that the unit is also compatible with an Apple remote control, which is a much better approach than trying to bundle a hideous off-the-shelf remote with the unit. The best aspect of the remote function, apart from being able to toggle volume up/down, is the ability to remotely cycle through the digital filters. This can also be done by pushing down on the rotary knob, but being able to do this remotely keeps my (apparently greasy) fingers off the volume knob.

 

The unfortunate aspect is that there’s no way to tell between which filter is engaged purely by sight. Engagement of both the IIR and apodizing filters is indicated by a purple Resonessence logo as opposed to the default blue colored bit perfect indication, whereas red is the indication for the state in which the Concero HP resides when no bus input, either USB or S/PDIF, is detected. It makes sense, then, that purple is the only possible result from the mixing of red and blue, but I would personally like to see at least a change in color intensity to differentiate between the two filters (perhaps add an additional white LED).

 

Sound

 

The Concero HP is simply the best-sounding USB-powered device that I’ve ever heard. There’s really no other competition.

 

Also, forget about the rumors you’ve heard that systems with ESS DACs in the chain sound analytical and dry — the Concero HP is anything but. It’s true, I’ve always been a “details-first” sort of guy, and while the Concero HP definitely impressed me on that front, the truly impressive aspects were peripheral to the rendering of details.

 

As expected, the level of resolution on the HP is immense. But the way the HP presents resolution, is one of those things where details are not “in your face”, but just plain easy to listen for. The best part about this experience is that the details do not feel distracting to the entire musical experience.

 

I felt that, for instance, the CEntrance HiFi-M8, a very capable unit in its own right, sometimes presented details in a fashion that detracted from an immersive musical experience. Conversely, the resolution rendered by the Concero HP manages to stay hand in hand with the required body of a stereo image, serving to enhance the listening experience rather than to detract from it. The details actually serve to help shape the dimensionality of voices, instruments, and harmonics, and I was discovering low-level details in familiar music that I previously never cared to examine.

 

The midrange, especially vocals, are front and center in the presentation of the Concero HP — black space surrounds vocals, isolating them from the instruments behind them. There is a slight analytical edge to the upper midrange and lower treble, perfect for how I like hearing my music, though admittedly, it might come off as slightly distracting for some. An HD800 will still show its 6k edginess.

 

Bass is perhaps the most satisfying aspect of the Concero HP‘s sound. It really brings out the best in more analytical headsets by extending as low as it gets and subsequently providing a deep and satisfying punch. The low-end texture and layering brought out by the Concero HP is truly an experience — it’s difficult to believe that something so small, and running off USB power, could output bass that is so low in distortion, tightly-wound, yet impactful — but believe it.

 

The two digital filters were also quite pleasant to use — while I ultimately preferred the more honest, non-upsampling default setting, I found myself listening to the IIR filter pretty often as well. If found that it lent more space to the soundspace, making instruments smoother, cleaner, and brighter. The apodizing filter wasn’t quite as smooth, as it doesn’t do away with pre-ringing, but it did manage to highlight individual elements in a track well, sometimes better than the IIR filter could manage. I found that different tracks and different listening moods called for different filters, and it was a fun experience cycling through the various filters to find the one that best suited the track.

 

With all this praise, what’s there to harp about then? Surely there must be something lacking? Instrumental separation.  It’s not world-beating by any means, and I’m sure a quality desktop rig can best the Concero HP in this area. Even the CEntrance HiFi-M8 managed to pull the stereo image apart a bit better. If you’re craving huge gobs of power and separation, the Concero HP won’t completely satisfy in this area. Even so, I was very satisfied with the performance of it coming from an HD800 or HD600. I never noticed anything being unreasonably small. The HP tends to be fairly honest about separation.

 

At 2.2 Ω, output impedance on the HP is not an ideal for multi-driver IEMs with wildly swinging impedance curves, but it’s certainly well within the realm of reason and not at all unforgiveable. Resonessence‘s new ultracompact Herus manages a much lower 0.2 Ω of output impedance, though, and the Invicta’s headphone amplifier likewise has an output impedance of around 1 Ω. It’s clear that Resonessence Labs understands the merits of good damping factor with a variety of headphone sources, even the most low-impedance models, but it’s too bad they couldn’t institute a lower OI for the topology they chose.

 

Overall, however, the Concero HP provides one of the most satisfying musical experiences I’ve ever had the pleasure of having. I just want to keep listening. It’s one of the few units that allows me to take off my analytical thinking cap and just bask in the cadence of the music being presented to me. If I want to put that cap back on,  I still have one of the best possible companions to dissect music with.

 

DSD

 

Direct Stream Digital has been the audiophile buzzword of 2013 — everyone’s starting to offer it as a supported feature in some way, shape, or form. Resonessence sure hasn’t missed the bus, and supports DSD on all its products, with the exception of the original Concero. So how does DSD work on the Concero HP? The Sabre DAC is a delta-sigma modulator, and thus decodes via the DoP (DSD over PCM) open protocol. Their website actually has a guide that instructs users on how to configure the computer correctly for DSD playback, but it’s a little difficult to find. Luckily, most tutorials online will give ample information on how to do it properly as well. Over Foobar, I installed the SACD decoder plugin and configured the ASIO proxy to work with the Concero HP via DoP. Everything went off without a hitch. Interestingly, all my visualizations went cold (you can’t “visualize” a 1-bit data stream).

 

Interestingly, I found audible differences between identical tracks coded in DSD and PCM. The “black space” of DSD was more apparent, and music felt livelier than its PCM equivalent. Unfortunately, I don’t quite know how to account for these differences, so I’ll just leave these simple thoughts as the are. Personally, I don’t feel the thirst for DSD — high resolution (and well-mastered Red Book) PCM sounds plenty good to me, but it’s nice to know that Resonessence has that format covered.

 

Usage Characteristics

 

If you noticed, my notes on sound characterization for the Concero HP have been qualified by the words “USB-powered”. At $850 CAD, the Concero HP is certainly the most expensive USB-powered unit I’ve ever encountered. Everything else that comes similar to it in size and intended use comes in at least a couple hundred less (examples: W4S DAC2-HD, Meridian Explorer, etc.). Then, not only is it the most expensive, it also sports one of the smallest feature sets in this category of DAC/amps, without RCA or balanced output.

 

So why the lack of utility? Other companies would’ve been crucified for this kind of glaring lack of connectivity. Even sub-$400 DAC/amp units these days include an RCA output and even throw in a 3.5mm output, in addition to standalone amp functionality. It’s certainly curious, since the Invicta is one of the most feature-packed DACs in its price range. You could surmise that the sound quality of the HP overcomes its shortcomings, but perhaps you’d only be half right. To really understand the spirit of the Concero HP, you’d have to examine where and how people listen to music.

 

At the core of the Concero product line is the philosophy of being a USB-tethered device — no power cords. Hence, a small unit like the Concero HP, while technically portable, would best be suited as a laptop companion that sits atop a desk. For true portability, the HP’s heft will bother some, but I like the weightiness of the unit. For me, the Concero HP fits perfectly into my commuter bag and allows me to haul it around with my laptop to various places. So, over the course of a working day, whether at home, at the office, or in a coffee shop, if you’re working on your computer, would you necessarily demand to hook up another amplifier to your signal chain, especially if your headphone amplifier is already so good? I know I wouldn’t. The Concero HP doesn’t have the extra connectivity simply because it shouldn’t.

 

While the tinkering audiophile may want to pair the DAC output with other flavors of headphone amplifiers, that job is more suited for Concero or Concero HD. The HP is intended to be a direct headphone portal to digital music, and that’s the way I like it. With it, I only need one unit for essentially all of my needs. It’s good enough to be a desktop companion, and small enough to take around. My portable amplifiers have been collecting dust ever since I started using the Concero HP.

 

Peek-A-Boo.

The Concero HP stows away neatly in the front pocket of my Mission Workshop Monty messenger bag.

 

Continual Improvement, Technical Service, and Promise for the Future

 

While the sound quality and features of the Resonessence Labs‘ products speak volumes about the company’s approach to audio, I’ve become a fan of Resonessence because of what they offer beyond the realm of hardware. Every company requires more than just a solid product; it also requires a product team that will continually tweak and improve on its products even after a sale has been made. Because D/A converters are intricately tied to computers, and with USB comes proficient coding of software controlling clock timing routines, the engineering team at Resonssence Labs has enabled firmware upgrades for its products that unlock new features or correct existing issues.

 

When I first fired up the Concero HP a couple months ago, it was running firmware version 2.2. After a few days of testing, I mentioned to Mark about a noise issue that cropped up during DXD playback. Within three days, he and his engineers had worked out the issue (they needed to disable S/PDIF output in DXD mode as the bit rate/depth is out of spec for S/PDIF) and uploaded the updated firmware version 2.3 on their website for downloading. I re-flashed the firmware, and voila, no more noise when playing back DXD files. I have no doubt that Resonessence Labs will continue to tinker with the code for HP and make it even better in the future.

 

With this kind of responsiveness and care, it’s clear that Resonessence Labs is very proud of the products they make — they’re a testament to their skill, but they back up that skill with a customer service effort that few others can rival. This attribute alone makes Resonessence Labs a company to believe in. When I received the Concero HP, I was at a bit of a crossroads in the world of hi-fi. I’d heard too many high-priced, hot ticket items that just didn’t seem to deliver. I was very afraid that the HP was more of the same. Luckily, it blew me away on first listen and it has continued to impress me. I was so incredibly impressed with the HP that within one day of using it, I informed Mark Mallinson of my intention to purchase the review unit.

 

There’s really not much I can say more about Resonessence Labs except to heap more praise. While there are certainly companies that have the ability to redirect consumers’ attention with a few flashes in the pan, I firmly believe that Resonessence is a company that is built for the ages. They have a very solid base for making great products, and they’re only set to expand. In the future, they’ll be able to boast a foothold in both the entry-level with the Herus, and the high-end with the Invicta/Mirus, as well as their upcoming stereo amplifier.

 

Resonessence Labs‘ company philosophy certainly isn’t a paragon of modesty: Our philosophy is simple: put together a team that includes world class audio engineers and design audio products without compromise. However, they’ve thus far delivered fully on those claims and I look forward to seeing many more great things from them in the future.

7 Comments:

Added Pictures! (2013/11/15)
Thanks so much for this detailed review!  Unfortunate about the OI as I would probably snag it in a heartbeat otherwise... have a JH Roxanne on the way - 15ohms/119db.  May have to wait on impressions with it first.  Also the Herus is on my radar, but going that route I'll hold off to see how the Geek Out fares.
 
Have you had a chance to listen to the Theorem 720?
The output impedance shouldn't be a huge issue, honestly. It'd be nice to have something <1 ohm, but 2 ohm isn't a deal breaker. Quoting impedance at 1 kHz isn't going to tell anyone much about the overall impedance curve of multi-driver IEMs. I would start to worry if the impedance of the Roxanne somehow drops to 5 ohm or so (a little low, even for BA drivers) at any point, but above that, it'd *should* be okay with the Concero HP. Also, depending on the polarity and electrical phase of the response, it'd be difficult to tell how the FR is affect from a lowered damping factor.
 
Here's the real reason why I wouldn't worry about the OI of the Concero HP with the Roxanne, however:
Jerry Harvey has people listen to it with the AK120, which has 2-3 ohm of OI --- basically identical to the Concero HP. If Jerry Harvey is okay with it, then I *assume* you should be?
No idea about the Theorem 720, unfortunately.
Fantastic point.  For some reason I thought the 120 was lower than that, but I do see it is rated at 3.  
 
Alright, I'll think about it a bit more, but this is most likely a buy.  Between John Grando/Darko and this review are all incredibly gushing for something of this size, form factor and cost.  I can 'treat' my TG!334s to a nice sonic upgrade during these couple months waiting for my Roxanne to arrive...
It's compelling reasoning, isn't it? Most of the measurements of the AK120 come off a DScope III, so there may be differences between it and the AP SYS2722 that Resonessence uses, but the general consensus is that the SYS2722 is the benchmark for audio test equipment. Resonessence doesn't seem to be the type of company to try to bend the truth on their measurements, either, so 2.2 ohms of OI should be quite accurate.
 
Didn't DARko write a little about the AK120 compared to the HP, in bits and pieces across several different articles, at least? Mind you, the TO GO! 334 will be able to pick up hiss on the HP (one of the few IEMs that does), but it's negligible. The 334 picks up hiss on just about everything I've ever used; I didn't do a comparison, but the hiss generated by HP is probably one of the lowest I've ever encountered, in any form factor, and definitely the lowest via USB power by far.
 
Of course, I think there are other units out there that can give you better cost-to-performance ratio, but nothing comes in this kind of form factor, and in that solid feeling a chassis. If you have the budget for the HP, I don't think you'd be disappointed in the least bit.
And with this I have been pushed over the edge, have one incoming, should arrive by the end of next week. :)  All very valid points - and Darko did, but I was just concerned about it specifically with the Roxannes.
 
This is for a rMBP rig that spends equal amounts of time on my desk and in cafes, so portability is crucial.  I was actually hoping for something more like the Herus form factor, but my impression is this is a couple notches up.  The $$ isn't as much of an issue as convenience.
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