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Resonessence Labs Concero

  1. planx
    Big sound, small footprint
    Written by planx
    Published May 25, 2013
    Pros - EXCELLENT value, Coaxial, USB, up to 44.1-384kHz playback, remote capability
    Cons - No Toslink, but that really isn't an issue
  2. project86
    The little DAC that could
    Written by project86
    Published Dec 19, 2012
    Pros - Exceptional sound quality - as DAC and as USB to SPDIF converter, good looks, small size, very aggressively priced
    Cons - Might not have enough inputs or features for some applications
    Not to pat myself on the back too much, but I was one of the very first people to review the Invicta DAC from Resonessence Labs ($3999). I found it to be exceptionally good - competing with and even surpassing several of my other DACs which cost significantly more. The Invicta system went on to become a very successful product, well reviewed by numerous other publications and (more importantly) highly enjoyed by lots of users. 

    One complaint, if we can call it that, about the Invicta was that it offered more than some people needed. This was tricky because the very reason that some people loved it - the all-in-one aspect with integrated headphone amp and SD card audio playback - was seen by other users as superfluous. I love the feature set Invicta has to offer but I can understand someone who already owns a top-level transport and headphone amp not wanting to pay more for those added features. There seemed to be a vocal group of folks asking for a similar release from Resonessence with "just the basics". Enter the Concero.... sort of.

    I'll just say this now to get it out of the way: At $599, Concero is not a stripped down Invicta with all the same parts minus a few goodies. That product may still be on the Resonessence drawing board but this ain't it, and if that ever does launch it will most likely still cost several thousand dollars. 

    So, what the heck is this Concero thing then, if not a cheaper Invicta? For starters, Ressonesence does mention that Concero uses the same processing engine as Invicta. That's not to be conflated as using the same DAC chip - it doesn't. The engine in question lives inside a Xilinx Spartan-6 FPGA running proprietary Resonessence code. This allows Concero to feature two user selectable upsampling filters, reportedly two of the most highly regarded choices out of the multiple filters offered by Invicta. Technically, Concero approaches this filtering differently than Invicta, relying on the FPGA engine to do the legwork while Invicta instead utilizes the highly-configurable filters in the ESS Sabre DAC chips themselves. I'm not exactly sure why this difference exists - perhaps the ES9023 DAC used in the Concero doesn't have the same configurability as the flagship ES9018 use by Invicta. Whatever the case, the end result should be the same regardless of how it was achieved. 


    At this point I'm going to do something I rarely do and refer the reader to another review site for details. This review at 6moons has a lot of good info in terms of the design choices made by the Resonessence team, and includes some commentary by Resonessence head honcho Mark Mallinson. I can't say that I agree with author Srajan Ebaen's conclusions all the time but he certainly does a good job covering the technical bits, and I have no desire to pester Mr. Mallinson with questions that have already been asked and answered in depth. Even if you dislike 6moons for whatever reason, I still recommend reading the first few pages for all the design info. 
    For those still not interested in reading that article, I'll give a brief synopsis of the Concero design highlights: ES9023 DAC chip, Xilinx FPGA, high-quality discrete clocks for 44.1kHz and 48kHz (and their multiples), galvanically isolated asynchronous USB input from Cypress Semiconductor handling up to 24-bit/192kHz streams, coaxial SPDIF input which can double as a transformer-coupled SPDIF output effectively turning the unit into a very competent Digital to Digital Converter (DDC): all this in a very compact but high quality enclosure. The front panel of the enclosure has a lighted "R" logo which changes colors based on the filter being used.

    A quick word about the bundled accessories: Resonessence handily includes an Apple remote control which is used to select upsampling filters and LED brightness, and provides simple transport controls for iTunes or other media players. The package also includes a USB cable and Apple wall charger - required to feed power to Concero when using the SPDIF input. Aftermarket power supplies, including battery units, could potentially provide some improvement here. 
    The Concero had some compatibility issues with my Auraliti PK90 music server connected over USB. It worked just fine playing 88.2kHz and 96kHz tracks. 44.1kHz and 48kHz files appeared to be playing but produced no sound at all, while 176.4kHz and 192kHz songs played with a terrible distortion. Mark Mallinson told me he'd look into it but it was likely an Auraliti issue rather than a Concero issue. The PK90 runs a version of MPD Linux but I don't have another Linux box handy to test - Resonessence makes no claims about Linux compatibility, so this application was a stretch anyway. All of the other USB sources I tried were running Windows 7 and all worked flawlessly at every sample rate. So this should not be a problem for the majority of users. 
    Aside from that, here is the list of gear used during this evaluation:
    Transport: Lenovo Thinkpad X1 Carbon, Acer Aspire One, Cambridge Audio 840C, JF Digital HDM-03S music server
    AMP: Violectric V200, Analog Design Labs Svetlana 2, Icon Audio HP8 mkII, Opera Consonance M-10S, NuForce DDA-100
    Headphones: Audeze LCD-2 (with Charleston Cable Company Auric Ohno), HiFiMAN HE-400 (with CablePro Earcandy), Beyerdynamic T1, Ultrasone Signature Pro, Heir Audio 8.A (with 93spec pure silver cable), JH13pro (new FreqPhase version, with Beat Audio Cronus cable), Lear LCM5 (with Heir Audio Magnus cable)
    Speakers: Salk Wow1 or Sjofn HiFi (the clue) monitors on Sanus NF30 stands, powered by the above mentioned NuForce or Consonance integrated units
    Power: CablePro Revelation 
    Cables: NuForce Precision SPDIF, CablePro Reverie AC cables, and a bunch of Auric and Auric Ohno cables from Charleston Cable Company - speaker, interconnect, USB, and AC
    I also spent a lot of time with the Woo Audio WEE electrostatic transformer, fed by the Consonance integrated and driving a pair of Stax SR-404LE earspeakers.
    As always I gave the device being reviewed a substantial amount of burn in (roughly 200 hours, maybe more) before listening. 



    Some DACs cause your jaw to drop at first listen, while others can initially seem kind of bland until you really get a feel for their character. The Concero seemed delicately balanced between those two - it immediately struck me as sounding clear and lifelike but didn't go overboard with detail retrieval. This is actually a good sign, as gear which initially stands out as being ultra-detailed will often later turn out to be fatiguing. 
    I started by playing some very nicely done hi-res material - Marta Gomez Cantos De Agua Dulce, Joel Fan West of the Sun, George "Wild Child" Butler Sho' Nuff, etcI was really impressed with the tonal balance and immersive soundstage, and I didn't hear any of the "digital glare" that many DACs in this price range are prone to suffer from. In general, a $600 DAC will provide a smooth "musical" sound that isn't all that accurate sounding, or else a nicely detailed sound that can be cold and uninvolving. It's rare to find both aspects represented in such a balanced fashion - at any price, much less $599. Concero simply stuns me with its coherency. At no point when using it did I feel that I was merely putting up with a budget DAC. That's not to say it competes on the same level as my pricier reference units - rather, it misses the mark in a very graceful way, that was not so easy to notice until I did direct A/B comparisons with the reference. This really is a great accomplishment on the part of Resonessence Labs. 
    Just be be fair, I followed up those squeaky clean audiophile albums with some real word music that I enjoy despite any sonic limitations - Sufjan Stevens, Matumbi, Kings X, Sister Sparrow and the Dirty Birds, Radar Bros., Pedro the Lion, Copeland, and of course the recently released Wait for the Siren by Project 86. The Concero is definitely not the type of DAC to sugar coat a bad recording. It won't take the edge off, but neither will it shine an extreme spotlight on those sonic imperfections. So while I didn't necessarily enjoy these albums as much in terms of pure SQ, I was still able to connect with them on a musical level. In other words - the Concero didn't try to fix them but also didn't distract me so much as to make them unlistenable which is something that plenty of other DACs can do. With these albums I tend to prefer a smoother DAC like my Yulong D18 but the Concero with apodizing filter will do the job (which I'll discuss more in depth later). Note that if we are talking about actual poor recordings, and/or low bitrate MP3 files, the Concero will do those no favors whatsoever. In those cases I do find it more on the "unlistenable" side and would much rather use some other design that is less resolving of artifacts. 
    With regards to system matching, I found that the Concero worked well with a variety of transports. The USB input always sounded great but I felt a slight improvement when using my ultra-clean Auraliti USB signal (with 88.2kHz and 96kHz material only, as mentioned prior). SPDIF sounded almost as good - both my HDM-03S music server and my Cambridge 840C did excellent jobs on transport duty. If I use a very highly resolving amp and headphones, I think I could perceive a slight lack of focus as compared to the USB input, but this difference was not huge. If my system only used SPDIF I would be completely happy with the Concero's performance despite it mostly being touted as a USB DAC. 
    The Concero was revealing enough to expose flaws in downstream components. Not that it was a poor match with any specific amps or headphones - a neutral DAC works with most anything. But it did show me the added resolution of my better amps, and it  did allow higher-end headphones to shine better than mid-range models. I really don't think the Concero would be an obvious weak link until you assemble a very high performance system. 
    I tried to get my hands on an outboard power supply but have not yet been successful. My Auraliti PK90 uses a SOtM tX-USB card which bypasses PCI power and sips directly from my external NuForce LPS-1. That probably explains why Concero sounded best when using it. Once connected as a USB device, Concero gives priority to USB over SPDIF, so I was not able to use the PK90 as a make-shift power supply along with SPDIF signals. I had an idea to deliberately crash the system so it loses the data connection but still supplies power - but so far I haven't been able to achieve that goal. I'll see if I can get my hands on an iFi iUSB power supply and update if I notice any difference. 

    A key feature of the Concero is the selectable filter options. The included Apple remote is used to cycle through - initial setting is no upsampling, followed by a minimum-phase IIR filter, and then a linear-phase apodizing filter. More info about these filters HERE Both filters upsample by a factor of 4 - so 44.1kHz material goes up to 176.4, and 48kHz material goes to 192kHz. Note that actual hi-res material at 88.2kHz or higher is processed at the native rate with no additional upsampling applied. The front panel glows based on what filter is selected, somewhat along the same lines as the Audioquest Dragonfly. 
    I tended to prefer the sound of filters compared to pass-through mode. The sound was more lifelike and palpable with upsampling engaged. Especially when I used a speaker setup, but also when using headphones, I heard both filters as having a more three-dimensional presentation. Standard pass-through mode was fine by itself but to my ears lost a little of the magic as compared with the other options.
    The differences between filters was pretty small but at times stood out like so: IIR filter seemed sharper, quicker, more precise, with better transient response (probably due to the lack of pre-ringing). It would be my first choice for playing exceptional recordings. The linear phase apodizing filter seemed a little smoother, more natural, more relaxed, but still plenty accurate. Resonessence lists this option as being a favorite among many of their beta-testers and I can absolutely see why. It's a better all around fit for a variety of music, amps, and headphones, and other folks who heard my Concero tended to prefer it the most. I remain undecided about which is my favorite and I'm glad they are both available.

    It's important to note that while the little Concero may be lacking a wide array of optical and AES/EBU inputs, it makes great use of the coaxial SPDIF port that it does have by allowing it to transform into an output. USB signals at all resolutions can be converted to SPDIF and transmitted to the DAC of your choice, with the benefit of extremely low jitter. Something unique to the Concero, that I have yet to find in another DDC, is the fact that it applies the optional filtering prior to output... so in effect this unit becomes an inline digital filter in addition to being a USB to SPDIF converter. Cool stuff.
    I evaluated the unit as DDC by comparing it to the well-regarded Stello U3 as well as the multi-function Izmo M1. Long story short, all three units sounded nearly identical in most cases. The Izmo fell behind by a small amount in a few cases due to lack of galvanic isolation on the SPDIF output. With most DACs this wasn't an issue and I would not feel confident trying to pick which one was being used. This may come as a surprise to HeadFiers who are used to reading about massive differences between each DDC device... but this is the way I heard it. All three units are very competent and operate on a very high level. 
    I did notice what I felt to be a worthwhile improvement by using the Resonessence filter options. Remember, these only apply to 44.1kHz and 48kHz streams, but they seem to enhance clarity and spaciousness to the point where redbook CD material doesn't seem like the wet blanket that it sometimes is made out to be. I'm only kidding here of course - so-called "standard resolution" recordings can be fantastic when done right. It's not that the Concero is adding anything to them via digital trickery; rather, it's just allowing the DAC to squeeze the absolute best from them. Keep in mind that this feature is optional and can be bypassed if the user feels it harms - rather than helps - the sound. 

    Rather than talking endlessly about how the Concero sounds, I figure it might be more illuminating to move on to some comparisons. Hopefully I'll have a comparison DAC on my list that you may have heard. Most comparison was done using the Consonance M-10S integrated, feeding the Woo WEE electrostatic transformer, then out to the Stax SR-404LE. It's a highly resolving system with multiple inputs for easy back and forth switching. The Concero has a lower output voltage than most others so level matching was important in order to compensate.
    Musical Fidelity M1DAC
    The M1DAC sounds better than the original M1 did (with the adaptive USB solution), but it still doesn't keep up with the Concero. The Resonessence unit simply does more of everything - deeper bass extension, more accurate timbre, a wider and deeper soundstage. This was one of the comparisons that seemed obvious to me, as if most anyone hearing the comparison would agree. The M1DAC does have more features like XLR outs and AES/EBU in, but in my opinion all the options in the world don't make up for a difference in sound quality this large.
    Matrix Quattro DAC
    This was more of the same, but to a lesser extent. I'd rank the Matrix unit above the Musical Fidelity but lower than the Concero. I dig the all-in-one approach that Matrix brings, with a pretty good headphone amp, pre-amp functionality, tons of inputs, remote control... but again - the sound quality difference is significant. The Quattro has a sense of hardness on the top end, almost seeming "glassy" at times, in contrast to the wonderfully smooth and open sound of the Concero. The Matrix unit sounds fine by itself most of the time - only A/B comparison brings out the flaws. 
    Music Hall DAC 25.3 
    This was a modified unit, with fairly extensive upgrades. I have never heard a stock 25.3 but this thing sounded bad to my ears. The slow, syrupy presentation sounded like it was overcompensating for a lack of ability by overly smoothing the sound to the point of mushiness. It had squashed dynamics and very little detail to speak of. So this comparison was not very good. Frankly, I've heard decent things about the stock unit, and I suspect the owner actually paid money to have some aftermarket company "upgrade" his device which actually degraded the sound. At least I hope that's true because there's no way the stock unit could sound any worse...
    Yulong D100 MKII
    This is my reference DAC in the sub-$1000 range. It's an improvement on the original which could come across as being somewhat analytical in certain situations. The MKII addresses that with some minor component tweaks plus a higher quality system clock resulting in a more balanced sound which is also more articulate. Before I get into the comparison, I'll repeat for the record - I love this DAC and continue to recommend it for many situations.
    After much listening, I've come to the conclusion that the Resonessence Concero sounds appreciably better than the D100. It's not a massive night and day difference, but it is there and it is significant. I especially notice it with high quality material from Reference Recordings, Mapleshade, Chesky, etc. The Concero just presents a more open, transparent window into the music, with a more realistic sense of space and a more fleshed out tone to individual instruments. The collective presentation is also more dynamic - which is surprising considering the discrepancy in physical size. I figured the beefier PSU of the Yulong would give it an advantage in this area but the Concero ends up having the edge. Speaking of edges - the Concero renders leading edges with more bite, and the overall sense of realism benefits. 
    So is the D100 MKII off the list in terms of recommendations in the sub-$1K category? No way! It's still a great performer for the price: plenty of inputs, an LCD display, balanced outputs, and a respectable headphone amp with a selectable filter for taming overly bright cans. For an all-in-one solution or just as a feature packed DAC in general, the D100 is still very highly recommended.
    Yulong D18
    The D18 is an exceptional DAC and a great value - it's a step up from the D100 MKII but remains reasonably priced at $699. I believe it's the cheapest unit on the market with the ESS Sabre ES9018 DAC on board. It has a burly power supply, a very high quality custom made low phase noise clock, and some clever design choices such as an SMA interface to carry the signal from input stage to DAC chip with minimal interference. In case it isn't obvious, I really enjoy this device.
    The D18 and the Concero couldn't be more different. Physically, the compact Concero is centered around its USB input, while the larger Yulong has every type of input but USB. Soundwise, they also veer very far from one another. Yulong has an ultra-smooth, spacious, warm, relaxing presentation that tends to make everything sound as good as possible. It's the DAC equivalent of a high-quality, forgiving tube amp which isn't overly syrupy but does add its own sonic fingerprint to the system. In contrast, the Concero  is more neutral, more snappy, more energetic and lively, without wandering too far into brittle, harsh territory. I prefer the Concero paired with my reference single-ended triode tube amp and a highly resolving (but not overly analytical) headphone like the beyerdynamic T1 for a clear, transparent window into the music. I like the D18 paired with the matching Yulong Sabre A18 amplifier driving the latest Audeze LCD-2 for a warm, smooth, musical presentation. Different setups for different music/moods, both of which I enjoy very much.
    If a person had the Yulong D100 MKII and wanted to upgrade but keep the sound signature within the same family rather than the warmer and smoother D18 sound, the Concero would actually be the logical choice.
    Peachtree DAC*iT
    I had never heard this unit before, and I ended up being really impressed by it. It does a lot of things right and considering the $459 price, I have zero complaints about it. I didn't compare the two directly so I can't be positive, but the Peachtree reminds me very much of the Yulong D100 MKII in terms of overall character. This is definitely a DAC I could live with happily.
    As with the D100, the Concero came out ahead by a reasonable margin. I was surprised to learn that the DAC*iT uses an "inferior" adaptive USB implementation because it sounds very good over USB, equal or better than the SPDIF inputs. Still, it doesn't have the same level of insight as the Resonessence, with a decline in low-level detail retrieval being the most obvious difference. The Concero also seemed more dynamic and "live" for lack of a better term, where the DAC*iT sounded more like a good reproduction of a past event. I've heard anecdotal stories of the Peachtree unit responding well to aftermarket power supplies but I didn't have a compatible unit available to try. 
    Audio GD Reference 5
    The Reference 5 sounds to me like an extreme version of the Yulong D18 - and I don't necessarily mean that in a good way. It has its charm, but the focus on density and weightiness seems to take precedence over transparency, and the overall result suffers. Interestingly, the Ref 5 manages a nice sense of spaciousness despite being somewhat too dark for my taste. The Concero doesn't quite rival the Ref 5 in depth or heft, but is clearly more resolving and accurate, and not in the annoyingly "lit-up" way you might be picturing. As I've mentioned, Concero is neutral and well controlled, rarely fatiguing unless the source material calls for it. 
    Overall these are two very different DACs. I prefer the Concero by a good margin but I could see how the Audio GD could be a better fit for some systems or some ears. The Reference 5 is discontinued and I'd probably recommend the Yulong D18 for lovers of this type of tonal presentation. Audio GD may have a corresponding current unit but I'm not familiar with their latest models. 
    Bryston BDA-1
    The Bryston, at its best, is very similar sounding to the Concero. The catch is that it takes very careful transport matching to get to that level - when using a mediocre source, it sounds merely good but not great. My Cambridge 840C is a prime example - using it as a transport, the BDA-1 doesn't really sound much better than the Cambridge's internal DAC. Different, yes, but not decisively better. Using my JF Digital HDM-03S music server brings things up several notches and shows the Bryston as having some real potential. The absolute best I've heard from it? Being fed by the Concero as DDC using the apodizing filter. 
    In a direct DAC to DAC comparison both models sound clean, detailed, open, and mostly neutral. The Bryston has a slight bit more "information" in the upper registers - call it brighter and more grating, or call it exciting and more detailed, depending on your point of view. Again I find myself surprised to hear the little Concero hold its own in terms of depth and bass impact, despite the Bryston having a more robust power supply section.
    Considering the extreme price disparity and the inferiority of Bryston's USB input (soon to be addressed in the upcoming BDA-2), I can't really find a reason to recommend the BDA-1 over the Concero, unless the user had a need for a broad array of inputs and balanced outputs. I find the Bryston to be a great sounding DAC and it is therefore very impressive that the Concero keeps up with it so well. Depending on the associated equipment, I actually find the Concero to be superior in some cases, despite the BDA-1 selling for over 3 times as much. 
    It's important to point out exactly what the Resonessence Labs Concero is and what it isn't. It won't replace your pre-amp. It doesn't have a plethora of inputs and outputs. And it doesn't have an integrated headphone amp. Those are things that people have often come to expect from a modern DAC, and to that end Concero might disappoint. It certainly isn't competition for its larger sibling the Invicta. Yet looking at it within the context of what it really sets out to do - this compact, focused little device is able to rival some far costlier models when it comes to pure sound quality. I'd go so far as to call it a giant killer, in terms of physical size as well as performance. Not only is it a great DAC, but it also excels as a USB to SPDIF converter, giving it that much more value.
    In summary, I'm immensely pleased with Resonessence Labs and their accomplishment here. This is truly a standout DAC in a field of great competition. With a lone exception, I really enjoy all the units listed in the comparison section above. Yet all of them fall short of the Concero in some area - performance, cost, size, or all three of those in some cases. This is a DAC that I'm happy to recommend without hesitation. Don't be fooled by its diminutive stature or price tag - the Concero is absolutely worth hearing. 


      Currawong, plainlazy and viper0700 like this.
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    2. customNuts
      On second thoughts, I didn't realise just how small this little dac was & that it was usb powered. This could be a great transportable dac with something like an O2 on top. That would be a nice little SE'd setup.
      customNuts, Feb 26, 2013
    3. jeffreyfranz
      jeffreyfranz, Jun 9, 2013
    4. jeffreyfranz
      Another fine review, John. Your relaxed writing style is a breath of fresh air for Head-Fi readers. Keep up the good work. - Jeffrey
      jeffreyfranz, Jun 9, 2013