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USB bridge mode. At $579 my Audiophilleo 2 was a perfect comparator. To retain fiscal balance, the Concero's S/PDIF link became Chris Sommovigo's budget Stereovox HDXV rather than heroically priced Tombo Trøn. I tried each box with native data rates, compared 176.4kHz upsampling in PureMusic's 1.86 software versus Concero's firmware and finally switched between the latter's three modes. The system was my usual Esoteric/APL Hifi UX1/NWO-M in S/PDIF DAC mode; a very expensive very good valve preamp on short-term reader loan (Concert Fidelity CF-080LSX2 with Psvane tubes); FirstWatt SIT1 monos; Aries Cerat speakers; and all Zu Event cabling except for USB.
Earlier the Audiophilleo 2 had out-resolved April Music's XMOS-based Stello 3. It thus became my permanent upgrade over the hiFace II OEM module built into my universal player/DAC. To further raise that setup, I'd then split not the atom but the USB cable (a KingRex uArt but Acoustic Revive, Elijah Audio, soon also iFi make them and surely others too) and plugged the power lead into Bakoon's very clever endless battery power supply. That was my USB audio status when the Concero touched down.
Now the Audiophilleo changed from clear winner as it had against the U3 to equality with a twist. There was a small difference to the Concero, albeit without causing any clear-cut preference. Either had its own attraction and the delta of performance was too insignificant for true advantages. The Resonessence felt slightly wetter. It was texturally softer and more pliant to exhibit a whiff of redolence or elasticity. The Audiophilleo was drier and thus more dialled for focus and wiry separation. For those who must have a victor, my vote would split depending on use. In USB bridge mode I'd favor the simplicity of Audiophilleo's cable-less solution but would have to give up on the Apple remote (more on that anon). In full-on DAC mode the Concero wins by default since the Audiophilleo lacks analog outputs.


Upsampling. PureMusic offers 64-bit NOS-type 'classic' and 'maximum fidelity' upsampling to counter Resonessence's twinned filters. With a Mac-based system one really ought to upgrade swiftly from iTunes to one of the better players. I slightly favor Audirvana 1.3.9.10's sonics but PureMusic 1.86 doesn't exhibit the beta's remaining Mountain Lion glitches. With serious users I'd call access to software-based upsampling fait accompli.
That perspective makes the Concero's filters not must-have deal clincher but mere alternate option. PM allows switching filters on the fly which inserts a 1-second mute. 'Classic' is softer and mellower, 'maximum fidelity' crisper and sharper. I tend to be a classic man but the liberty to lightly season with salt or sugar is great when equipment changes constantly as it does for reviewers. That said, I couldn't determine which approach to upsampling was superior, iMac or Concero. Plain for either? By being smoother fuller and more fluid, integer 4 x upsampling bested native Redbook each time. Deciding between Canadian IIR and apodizing filters was a far closer call however. I imagined a minor preference for the latter but as Mark Mallinson already suggested on the previous page, this seemed fickle based on exactly what music I played.


The upshot is, these filters are a remote click from the listening chair. You decide what you like best in the moment. Chances are you'll rarely see blue. Here I admit to Better Home shallowness. I prefer keeping my various hifi LEDs to one color rather than lighting up like Las Vegas. This would have me end up with iMac upsampling so the Concero's blue matches the Esoteric and amps. As a hifi color magenta and our household are a clash. Such superficiality also tells you just how inconsequential the sonic considerations were on where to do the (integer!) upsampling as long as it got done. That's no blanket endorsement for upsampling but specific to these machines.

As USB DAC. The $479 KingRex UD384 is the Concero's Asian cousin. It too is a clever 'DAC on a chip'. It too offers USB bridge mode or analog outputs for complete conversion. Core differences are AC power—which can be upgraded to battery with the matching $189 UPower—and 384kHz data reception. In this context the Concero's convertible i/o S/PDIF socket is unique. The Canadian also retains cosmetic edge by keeping socketry on the back. The KingRex mounts it to both ends of its smaller extrusion and fouls up out-of-sight cable dressing.

What one thinks of these boxes as DACs depends. Far costlier kit digs deeper on tone and impact for a more complete in-room illusion of a foreign acoustic superimposed upon your own peopled with tangible presences. It's why the Invicta exists. Coming upon Concero or UD384 from there strips things away. Think line drawing whose artist hasn't completed full-color fill. Shapes and perspectives are in place. The orchestra is seated, the conductor has arrived. But not all lights are on. Even so what's there is an excellent reminder on how far things have come. Lacking a higher reference you won't know what else is possible. Talk of any 'missing' is balderdash then. Let's go to that place now and compare these two affordable black boxes on their own merit.
KingRex UD384 with undisclosed main processor engine

With Audirvana set to max upsampling—176.4kHz for the Concero, 352.8kHz for the UD384 just because it could—the KingRex was more emphatic gutsy and guttural. The Concero again played it softer, gentler and rounder. The UD384 was more forward and seemingly tuned for energetic adrenaline and the urge of rhythmic drive. The Concero 're-angled' the lights to shine deeper into the virtual stage and feel more relaxed and concerned with space. For my money the KingRex had a small edge. Now I wondered. In keeping with propaganda, would another DAC in this price range hold any advantages just by running discrete output devices? At $449 Schiit's Bifrost with optional USB would surely have one possible answer. 'Just warm me up properly first' was its request. Heeded. An hour later these games resumed.

Disappointing to the 'ICs suck' faith, I heard no advantage for the Schiit. With output levels matched to account for the Concero's 1.2V handicap, I in fact thought that the maple leaf mini—by comparison the small Schiit is a giant—had the more finely rendered contrast or focus. This wasn't a function of retracing outlines to emphasize edges. This felt more like a noise floor-related observation. There the degree of differentiation between no-thing/silence and yes-thing/images goes up. It's impossible to extricate this impression from a related one which cues into the difference by hearing slightly stronger tone colors. I think 'color depth' and 'image lock' are interdependent and two ways of considering the same thing. Here the Concero was a tad glossier, the Bifrost more matte by contrast. Once again these offsets were about subtly different flavors rather than winners and losers. My takeaway was that for the same money (here I added a decent $150 power cord to the Schiit) the Concero was physically smaller, more widely featured and every bit as good.

Finally I stretched my comparator budget to $899. This buys you the recently reviewed Asus Xonar Essence One Muses Edition whose 'axeome' acronym just misses axiom and awesome. I'd recently reviewed it before former contributor Michael Lavorgna awarded it AudioStream's Greatest Bits award for easy consensus on value and performance [click right graphic for his review]. With Taiwanese/Chinese manufacture and coming from the world's 5th-largest IT giant, value was a given. That machine's feature set, parts quality and execution are bound to overshadow Western resources on like coin. We'll disregard that plus the usual subtext to focus on a pure ear vote instead.

(Though the dual-mono op-amp ensconced Asus runs a dual-differential circuit, I used its RCA outputs because it was the more likely scenario in this price range.) Here the tables turned. The luxury opamps from New Japan Radio Co. Ltd called Muses 01 with Mosfet inputs were beefier and warmer particularly in the all-important vocal band. This moved the overall Asus sound in the Burson direction; what in the past I've called the textile/silk-dome school as opposed to the ceramic/Beryllium sound. Unlike the earlier A/Bs above now the Resonessence was outclassed. Spending 50% more on a super high-value Asian challenger did climb a clear rung up on that endless ladder in the sky of audiophile lust. This completes my attempts at assessing the Concero's standing within a bigger picture.


As a USB bridge it competes head-on against the deservedly popular well-proven Audiophilleo 2 which in my book situates it above the U3. As a full-on DAC—USB or coax input—it competes directly against the KingRex UD384. Invoking the small print of "these types of differences were minor!", its particular sonic gestalt was flow over attack, space over forwardness and a very slight roundness or softness. The on-the-fly selectable upsampling filters built in a small shifter to impact those attributes. Here the Concero is unique in its class. Upsampling with different filters is of course also possible in software but there often lacks the Concero's from-the-seat remote convenience. Playing 'on the level' held against Schiit's Bifrost where I actually thought the Concero had a small edge on color contrast. In the context of an expensive system where the Concero's analog outputs no longer keep up, its coaxial output in USB bridge mode remains highly viable and at least on the order of the popular hiFace II* which shows up in many a very costly converter as an OEM module.
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* I reached that conclusion based on the Audiophilleo 2 besting the hiFace II built into my player and the Concero being a stand-in for the Audiophilleo though not identical.

The plain truth is, I'd use the Concero as USB input for my €30.000 NWO-M in a heartbeat! That's in fact how I see the Concero's ongoing appeal. Start using it as D/A converter. Once your sonic needs begin to eclipse what it can do, repurpose it as USB bridge and be set for the very long term.


Cheap fix. When Resonessence reported inability to replicate my minor dropouts on their new Cambridge iD100 dock—theirs worked just fine—I went to my next-door hifi repair shop slash Pure dealer. He ordered me another i-20. My digital docking around had gotten me from Onkyo to Pure to Cambridge. Each time I'd made a brand change, the previous units were gifted to friends. At $99 the Pure is dirt cheap. Just so it ameliorated the iD100's occasional dropouts on the Concero and—hurray—played nice with Burson's Conductor which hadn't liked the Cambridge two bits (something Burson confirmed). I don't know how or what went funky with my two iD100. At 60% less, the humble Pure i-20 simply streamed flawlessly to save money and grief for a true win/win. It also settled my concerns that my iPods had gone soft to stream erratically. The culprits were my Cambridge docks - perhaps worn contacts in their 30-pin connectors?

Sonos. Lumos. If HP—Harry Potter to you—had an audiophile spell, he'd now cast it to illuminate what the Concero sounds like. The Sabre chips have a rep for 'extreme' resolution. This could conjure up fears of being overly analytical. Not. Compared to the AKM 4399 favored by Schiit and the USB:D/A in-one chip which KingRex remains mum about, I encountered no such thing. These particular roads all led to a Rome that was sunny but not on a merciless summer day without shadows or half tones. Discrete or on chip, silicon a, b or c, the results were quite interchangeable. What impressed me about the Concero was its subtle hint of moisture which countered the dryness one can find in more budget DACs. Whilst the small Canadian won't do body, warmth and fleshiness like the Asus begins to do and the Burson Conductor elaborates on much further, it's not a whitish 'stripped' sound from the Nordic snow lands. In fact there's a hint of sheen or gloss to tone colors.
Where bigger budgets buy more heft, dynamic impact and overall scale too, what the Concero delivers on soundstage mapping and low-signal retrieval for ambient data is quite advanced already. Mated to a stand-mount speaker like perhaps a Paradigm or PSB to stay on budget, you'd be surprised at all the imaging cues and visual elements this small black box pulls out of its hat.


How Sabre 9023 competition like Wyred4Sound's $399 µDAC—limited to 24/96 on USB—or $499 µDAC-HD (24/192 async USB plus headphone output) stack up I don't know. But that wasn't on today's menu either.

What team Resonessence brings to the party besides fully competitive sound are the added features of convertible coax (input or output), selectable upsampling with two different filters and the hijacked Apple remote. The latter comes in handy for playlist 'next' commands and the occasional 'pause' when the phone rings. Here the infrared link to the Concero reaches farther than my iMac. That tends to be out of range from my listening seat where the Concero still responds. For this anti-wifi fossil in self-imposed exile from the iPad remote—until someone figures out a wired solution—that feature was most welcome. And here's a bit of real-world news. When sonics are a go as they might be with a different hardware choice, it's often such small 'soft' non-sound items that ink a deal. Here let's not forget flawlessly finished tank construction. When I add it all up, the Concero is a clear winner all the way to the missing 't'.
Resonessence Labs website