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Resonessence Labs Concero DAC review (TONEAudio)

  • I wanted to call this article: What’s wrong with USB?

    The problem?

    1. Resolution. Yes, sample rate compatibility has nearly always lagged behind the steadfast 24/192 of most S/PDIF inputs. Even two years ago many a DAC’s USB input would only decode up to 48kHz sample rates. This is slowly improving.  Some examples?  Sure!  The now ubiquitous XMOS chipset has seen Peachtree lift its iNova from 24/96 compatibility to the Nova125‘s 24/192. Ditto Emotiva: their XDA-1 maxed out at 24/48. Its successor – the XDA-2 – now runs up to 24/192. Curiously, it can’t do 176.4kHz. Neither can the recently reviewed Wadia 151PowerDAC Mini but I cut it greater slack as it was launched way back in 2010 when 48kHz USB was more the norm. The 176.4kHz sample rate hole is annoying if (like me) you happen to prefer 4x software up-sampling on Redbook material. If you’re in the market for a new DAC, scour specification sheets and reviews to ensure your shortlist models can handle 176.4kHz and 88.2kHz.


    2. Sound. No, I’m not trolling. I’ve said it before and I’ll say it again: the sound from the USB input on nearly all DACs (that I’ve heard) falls short of its neighbouring S/PDIF input. That’s assuming the DAC can do both. I know this from regular and consistent deployment of USB-S/PDIF convertors. Manufacturer marketing departments are understandably coy about this USB performance shortfall. They’ll hit you with words like ‘asynchronous’ and ‘world class’ (what does the even mean?) and hope you’ll let your credit card fly. That’s business!

    The solution.

    When you buy a DAC, buy a USB-S/PDIF convertor too. You’ll be grateful that you did. This kind of DAR reader email is not uncommon:

    “John – I took your advice and bought a convertor to feed the DAC in my desktop system. (ATM it’s a Channel Islands VDAC from my main rig but I’m looking for a replacement). It’s only the Musical Fidelity V-Link 24/96, but the difference it has made is dramatic. Better imaging, far more relaxed and natural sound. Previously unpleasant-sounding discs now sound fine.

    So many thanks – Bruce”


    My experience with the likes of the Wyred4Sound’s uLINK and – more recently – Resonessence Labs’ Concero always sees me ultimately ignoring the DAC at hand’s USB socket in favour of its coaxial S/PDIF*. Not only do these devices re-clock data – less jitter for you – they also buffer the DAC from the electrically noisy computer. With a Concero or uLINK in the chain the DAC is no longer directly connected to the host computer; the DAC is (to some extent) protected from the computer’s EMI/RFI noise. Moreover, these convertor boxes open up all sample rate possibilities to 192kHz (with no 176.4kHz hole).

    Resonessence Labs’ Concero is the first device to finally pull up alongside the previous budget champion from Philip Gruebel. The Concero’s sound is damper and smoother than the Audiophilleo2**. Moreover, the two in-built up-sampling algorithms in the Concero can be switched in from any Apple remote – the CPU-intensive 4x up-sampling can be externalised. Oh yeah – the Concero can also stand alone as a great-sounding DAC. How much? US$599.


    You can read my full review of Resonessence Labs’ Concero in the Issue 53 of TONEAudio. Download the FREE .pdf here.

    Further Information:  Resonessence Labs | Addicted To Audio


    * The Metrum Hex’s M2Tech OEM USB interface doesn’t take 5V from the host computer. It has its own internal power source. This is the only DAC I’ve heard to date whose USB sounds as good as the Concero feeding its S/PDIF.

    ** I’ve heard from several sources that the PurePower-modded Audiophilleo (AU$1099) is one of the best sounding USB ‘transports’ currently available.

    John Darko

    Written by John Darko

    John currently lives in Berlin where creates videos and podcasts and pens written pieces for Darko.Audio. He has also contributed to 6moons, TONEAudio, AudioStream and Stereophile.

    Darko.Audio is a member of EISA.

    Follow John on YouTube or Instagram


    1. I’m traveling and a friend borrowed my v-link2. He liked it so he bought one too. Out of sheer exploration he hooked the two one after the other to his setup… and said the improvements were obvious compared to one. Ain’t that some crazyness !?

    2. Hi John,

      will be the M2Tech hiFace Two converter good enough, can you recommended it? I have Burson Conductor connected via USB with constant problems with non-native 64 bit drivers and low latency issues.


      • The Hiface2 is a good jumping off point into the world of USB-S/PDIF convertors. However, the Concero and AP2 are much better sounding devices.

    3. Hi JD
      I’ve no doubt your call in many instance’s regarding sub par USB implementation. However, in my limited experience I have found particularly over the last 12 months or so USB catching and overtaking S/Pdif. Case in point is the very impressive and well priced Wadia 121 – its USB output is clearly a step up from its S/Pdif option in my view and in my system. Less is usually more and the less ‘links in the chain’ the better in my experience – not to mention the financial saving.
      Keep up the good work!

    4. Hi John!
      Straight to the point and very informative, as always 😉

      You might want to look into the new .32 Audio-GD DAC offering.
      The built-in USB input is top notch (some say on par with the AP2 + PP. I didn’t go far in comparing it with my (ex) Stello U3 but it was no downgrade for sure!).
      And it doesn’t take the 5V from Computer either.

      Especially the Master-7, the evolution of the Ref-7.1 you seem to like a lot.


    5. John..
      You should check out the new update from Audirvana 1.4.6 The integer mode update seems to have improved the sound considerably.

    6. First- terrific website John.

      It is refreshing to have a website where the owner has the same musical interests I do, rather than the stereotypical classical, jazz, Diana Krall stuff (nothing wrong with those genres, I listen to some of that music, just not all the time).

      I share your views on USB-SPDIF converters and the superiority of using such devices rather than going directly from the computer to the DAC via USB.

      I a currently own the Bel Canto uLink, as well as the AR-T Legato 2 (redbook only, but man, does it sound spectacular). I have the Bel Canto Reflink in for a demo at the moment as well. All 3 are stellar units, and significantly improve the sound of my system as compared to going direct to the DAC.

      P.S. I have to disagree with you about Andy Stott: Luxury Problems, but rather appreciate you turning me on to Lambchop: Is a Woman.

    7. John,
      Have you had a chance to hear the Wyred4Sound μDAC? It seems to be a direct competitor to the Concero as it also uses the ES9023, has USB and S/PDIF inputs, and is around the same price range. I’m very curious to see how it compares with the Concero as a DAC, especially since their μLINK seems to be pretty well implemented.

      • No, I haven’t. Sorry. Lack of time. My next review of a W4S product will likely be one of their amplifiers…

    8. Asynchronous is only a very small part of whether the USB performance of a DAC will be any good or not. The original and very lousy sounding M2Tech Hiface was asynchronous. So is the Audiophilleo2 and the Off-Ramp 5: possibly the best converter on the market with the possible exception of the megabuck Stahl-tek converter.

      Asynchronous is better than the alternative adaptive mode, but there’s a lot more to it than that. The first thing you have to do is galvanically isolate the input. Converters can isolate their S/Pdif outputs instead, but if the USB input is on the DAC and goes straight to I2S, you have to isolate it. For whatever reason Meitner/EMM opted not to do that, so even the USB input on the $15K EMM DAC2X will be beaten by a properly isolated converter.

      The second thing you have to do is dump the Vbus power. Bus powered USB DACs or DACs that use bus power to drive the USB circuitry instead of internal power will never sound as good as those that are self powered. The reason is that the 5V coming out of the USB bus is INCREDIBLY noisy.

      So you’ve got asynch, and the input is isolated and self powered. What else can you do? Well if you’re just connecting your DAC to some random motherboard port, you’re not getting the best performance. A combination of the iUSB or SoTM USB card and Empirical Short-block are better options, but the best route is to sever the electrical connection entirely. The iUSB and the SoTM card supply their own power (or the SoTM can cut the power off if it’s not required) but both still have a common ground path. The Short-block reduces the effects of that ground path, but can’t completely eliminate it.

      The Adnaco S3 card eliminates it by using fiber optic cable for the data stream. It terminates into a box with two USB 3.0 ports which are powered by a wall wart. Replace that with a linear PS, and you’re pretty much gold.

    9. Sure. It’s also important to not neglect the rest of the computer. Laptops are popular for music servers but they are very poorly suited to the role – no PCIe slot, and they aren’t designed to run at a fixed clock speed.

      A dedicated server box is a much better choice, and the Computer Audiophile CAPS is a very good reference on what to use. A RWA battery supply is the suggested power source, although a good linear supply should work just as well for less cost. Properly configured, a CAPS style server box (especially with the Adnaco card) should be able to match high-end servers like the Aurender S10 for about 25% of the price.

      • I agree. But I also think that a fairly standard PC with an Audiophilleo or Concero PLUS an iFi iUSBPower device *might* be just as good.

    10. Depends. If it’s a general purpose PC that’s running AV software, has a keyboard and mouse going through the USB interface, and is otherwise running software and peripherals that aren’t directly related to audio playback, all of that is ultimately going to hurt sound quality.

      Ideally, a computer server box should be run headless, without a monitor or any sort of input devices – USB all ultimately ends up in the same place. It should run the bare minimum amount of software possible, either Windows stripped down to the bare essentials in JPlay’s hibernation mode or something like JRiver or Foobar with Fidelizer, or something like Vortexbox and MPD.

      For devices that require a USB power feed like the Concero, there are a few ways to get there. You can use a Y-type cable with something like the KingRex or Bakoon batteries supplying the 5V power, or you could use the SoTM card and power it with the SoTM battery, or you could power the iFi with a battery.

      Probably the best options would be: 1. Computer > Adnaco S3 with LPS power > Concero, or 2. Computer > Short-block > iFi with LPS power > Concero.

      • Dave- why use a battery with the iFi? That does not make any sense. iFi has a white paper and conducted tests and the iUSB’s power is cleaner than that provided by a battery source.

        I run: MacBook Pro > Audirvana + > iFi iUSB > uLink (when using my AR-T Legato II, I don’t use the iUSB as it is not needed) > DAC > amp > speakers

      • ..forgot to mention, I also use a KingRex uArt Y USB cable to take advantage of this option in the iFi iUSB.

    11. If the included power supply with the iUSB is switch mode, that could definitely be improved by replacing it with a battery. If it’s a linear supply, a battery likely wouldn’t be necessary.

    12. Sorry Dave, while I do agree with a number of your generalized comments, you are not correct with respect to the iUSB. I sincerely do not intend this to be a snarky comment, but I think you need to read up on the iUSB before making generalized comments about improving this device, as your suggestion is absolutely incorrect (using a battery with the iUSB and comments about SMPS). Clean power is the iUSB’s raison d’etre. The suggestion to ‘improve’ this device with a battery is silly. Suggest you read up on the iFi iUSB before suggesting tweaks to this particular device, lest you steer a newbie down a wrong path and wasting of money.

      • Thanks for that link, Blake. I’d not seen that. I wish iFi/AMR would put this stuff on their website too…

    13. Hello,

      Just back from the Montréal HiFi show, the people from Resonessence Labs told me that a Concero DSD compatible is coming.

      Just so that you know.



    14. They ( Mark M) say late this month they will starting taking orders for this $800 DSD Concero which uses the ESS Sabre 9016

    15. A Q for JD and the rest
      If instead I use an optical output (have it on my sound card) to both isolate the noises from the PC and to avoid the USB connection, will this work good?


      • The Concero has no optical input so I suppose your question is more general.

        Yes, optical link – by nature – is galvanically isolated (optocoupler) and, as such, will isolate noise from your Computer (and most EMI that might surround your equipment).
        It also comes with its own shortcomings, among which, a higher level of jitter which lead to poorer results than a coaxial connection, in general.

        At first, you might actually hear more details in the sound (a more sharp/incisive sound, if you will) but these are mostly digital artifacts that will quickly become tiresome.

      • Some folk reckon optical to be not as good as coax (slower rise times) but you should use what SOUNDS best to you.

    16. John,

      I am looking to jump into computer audio. I plan to use an iPad 2 & CCK. Research indicates that USB DAC compatibility is the biggest challenge to using the iPad/CCK.

      Schiit has confirmed that their DACs are compatible with the iPad/CCK; however, based upon various reviews/forums the Gungnir would be my choice: $850 – ouch.

      Is the RL Concero directly compatible with iPad/CCK? Does the Concero compare well with Gungnir?

      Other recommendations for iPad/CCK?


    Audio-gd Master 10 w/ Magnepan MMG (6Moons)

    Graham Slee ‘Bitzie’ DAC / headphone amplifier