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Resonessence Labs INVICTA Mirus review

  • Savvy silicon sleuths will probably know that Brit-brothers Mark and Martin Mallinson head up Resonessence Labs and ESS respectively. When family ties connect chip maker and DAC baker, cross-pollination of technical talent is all but inevitable. Brother Mark’s engineering team were directly involved in the design of the Sabre 9018 and wanted to see what could be done with this chip in a system level product. Resonessence Labs was created to do exactly that.

    The Resonessence Labs’ Invicta Mirus (from hereon called simply ‘Mirus’) is an iterative development of their original statement unit, the Invicta (US$4995). Essentially, the Mirus (also US$4995) is the product update for those who don’t do headphones. Previously funneling data to the headphone output, the second ESS chip has been relocated to the backboard for dual mono conversion layout – one ESS 9018 each for left and right channels.


    The Mirus can decode DSD64, DSD128 and PCM up to 24bit/384kHz. With two Sabre 9018 chips running in parallel, the Mirus’ measured performance improves on its forerunner with a 5db lift in dynamic range to 130db. Those with a thirst for numbers can gorge themselves over at the Mirus’ specifications page here. However, measurements won’t (necessarily) tell us how it’ll perform in real-world environments.

    Rear-panel digital inputs are identical on Mirus and Invicta: asychronous USB and toslink are standard practice nowadays but twin 50 Ohm BNC sockets are not. The third BNC socket has yet to be allocated as input or output but it’s something that can be allocated at any time from a simple firmware update to the FPGA. It’s this chip that marshals the entire Mirus data system. Resonessence Labs’ FAQ details the whys and wherefores here.

    The USB receiver features in-house developed custom code on a Cypress chip. A Thesycon driver is needed for UAC 2.0 compliance on Windows. “We had considered developing our own USB 2.0 driver at one stage but we decided instead to license an existing one to save time,” says Mark Mallinson.

    The output stage of AD797 op-amps sees daylight through balanced XLR (4.6V) or single-ended outputs (2.3V). On this Mallinson opines, “We don’t believe discrete or op-amp based is superior by just quoting the topology. The implementation is the key. It’s like asking what team will win the F1 without knowing who the drivers are. Both can be phenomenal and both can be terrible. It’s really how the whole system works together that brings out the quality. Simply buying a low jitter clock and putting on a PCB doesn’t make the DAC see a low jitter clock coming in. Implementation is what separates the wheat from the chaff.” Implementation, implemnetation, implementation. Agreed.


    As per the rivalling AURALiC Vega, the Mirus comes with a selection of digital filters, designed to remove anti-aliasing artefacts from the digital signal. Two come from the silicon maker ESS and five are home grown. Cycling through each filter in turn solicits sonic deltas that are impossibly subtle (the details of which are beyond the scope of this review).

    In trying to nail the Mirus’ core sonic qualities I kept returning to two words: density and smoothness. The Canadian implementation sounds quite different to the AURALiC Vega’s high megapixel take on resolving finer details and textures. An afternoon of switching back and forth between these two Sabre-rattlers – each connected in turn to a Lumin S1 over S/PDIF – had the Mirus establish itself as the detail retrieval equal of its Chinese counterpart but in doing so it sounded more reserved, wetter and not as obviously separated. The Vega brings an ultra-vivid take to tonal colours that’s a mite chalkier than the Mirus. On percussion and vocals, the Mirus played it less overt and sounded more linear; a mid-bass-centred room node was more pronounced in AURALiC hands.

    The Mirus better communicates music as a whole rather than the sum of composite parts by showing greater homogeneity with tonal density from cymbal brush to low kick. The Vega is more about layer separation and precision. In choosing between a rainbow of flavours (AURALiC) or home-made fruit cake (Resonessence Labs), I’d anticipate a 50-50 split amongst those considering one or the other.


    It’s clear that the Resonessence Labs engineers have paid close attention to the volume control: 32-bit digital that’s audibly lossless with Redbook content for the upper sixty percent of its range. As reported some time ago when reviewing the mAMP monos from Wyred4Sound, there was scant evidence of the inward soundstage collapse or ongoing thinning of acoustic mass when running DAC-direct (aka sans pre-amp). Those wanting to maintain full meat-on-bone will likely still want for a pre-amplifier proper whereas those opting for DAC-direct will need a power amplifier of appropriate input sensitivity to keep the Mirus attenuating in its upper half – a much easier task than with the AURALiC Vega whose hotter output demands more insensitive downstream loading to keep it digitally attenuating in its critical upper quartile.

    Volume levels displayed on the Mirus’ blue OLED are easily discernible from the listening position. Track info is not. For that we tap another new feature not available in the first generation Invicta: HDMI as video output. Hook it into your TV and presto! The third-screen visual aesthetic might be plain but it’s effective in allowing for complete O/S navigation from the sitting position when deploying the (supplied) Apple remote control – a simple but effective hardware hi-jack. Lose the remote and it’s replaceable easily and cheaply. Failing that – or for the user that likes to get up close and hands on – the rotate-and-select jogwheel offers plenty ergonomic satisfaction.

    The Resonessence Labs casework connotes glossy utilitarianism. Think an upmarket Mytek that’s far less prone to dings than the sleeker looking AURALiC. The half-width casework of the Mirus ensures greater flexibility with positioning. I sit mine atop a PS Audio NuWave Phono Converter for easier S/PDIF connection between the two; I listen to vinyl digitally. Take that purists! With 24-bit/96kHz PCM, I have a hard time qualitatively separating the (analogue) output of the PS Audio and the Mirus – they both sound as if each were cut from similar cloth. In moving from PCM to DSD the delta between phono stage and DAC begins to bear fruit. The PCM possesses more jump factor and caffeination whilst the DSD stream dilutes and softens (some of) the transient cayenne with moist cotton wool which results in a more billowy take on things. Yup, the Mirus is able to receive a stream over its USB connection AND over either of its BNC inputs.


    And then there’s the SD card slot. It’s the Mirus’ most significant point of difference; one that facilitates firmware updates and – critically – transport duties, permitting music play back without the need for feed (from a music server or disc spinner). Drop some tunes onto an SD card, insert into the Mirus and you’re off uptown.

    Since the Invicta’s 2011 debut, regular firmware updates to the DAC’s FPGA have seen SD card file format accommodation extend from strictly WAV-only to encompass AIFF, FLAC, DFF and DSF, all of which maintain pace with the S/PDIF and USB input sample-/bit-rate compatibility. SD card contents are navigated via folder structure on either the OLED or off-board HDMI-connected display. The Up/down, select, back (“menu”) controls of the Apple remote are intuitive but browsing AND playing are mutually exclusive operations.

    The data flow from SD card to decoder runs like this: The source file is decoded into RAM where it becomes normal lossless PCM data, after which it is sent to a FIFO (first-in-first-out) buffer before being transmitted to the DAC via I2S.


    Before reaching full tilt in praising the SD card transport I must first call out a couple of minor niggles.

    Whilst transport controls are responsive and graceful, Resonessence Labs’ engineering team haven’t quite nailed gapless FLAC; in transitioning between tracks there’s an audible stumble. It’s far from the worst gapless implementation out there but close enough isn’t the same as seamless. In conversing with Mallinson about this issue he assured me Resonessence Labs will sort gapless with a future firmware update. “We started out with software version 1.0.0 . We are now on 6.0.2..tons of upgrades based on user feedback, a theme that we will continue”, he says. I can personally attest to Mallinson’s team’s speediness in ironing out wrinkles when the aforementioned PS Audio NWPC couldn’t initially talk DSD turkey with the Mirus. I had a firmware fix (from both parties) inside two weeks.

    My second grumble remains beyond Resonessence Labs’ control and probably won’t impact every Mirus owner. Impatient users should ensure the use of the fastest SD cards available. Loading a FAT32 8Gb Sandisk SDHC took around 2 mins per 700Mb which translates to roughly 20 mins required to fill to the brim. Faster transfers might not be a priority for everyone but in Sandisk land, the faster ‘EXTREME’ cards will see your media spend quadruple.


    Moving from S/PDIF feed to SD card source solicited minor differences in the Mirus’ delivery: blood-flow quickened adding a heightened sense of separation and alertness. The Mirus now sat closer to the Vega’s ultra-brilliance by letting more light in from below. Curiously, the Mirus’ SD card soundstage front-line sat a step or two behind that of the S/PDIF bowel-feed take.

    The biggest headline is this: if there were an audible difference between SD card playback and the Antipode DS music server lassoed with Light Harmonic LightSpeed USB cable, I couldn’t pick it. Wowsers! The implications here are significant. The SD card transport isn’t for twitchy fingered fiends who simply must have everything available, always. For those content to build a catalogue of cards and who are happpy foregoing the immediacy of their entire collection, the audiophile music server can be dispensed with. This is a solution for people who baulk at a computer in their rack (or even lounge room). With the Mirus in SD card mode, one’s PC + external HDD + SD card reader can now be housed elsewhere for library storage with the user dipping in at his or her leisure; the time required to load a card being the limiting factor.


    The SD card slot is also good news for visiting friends and relatives. Like Bluetooth streaming, it’s inclusive and it’s easy. No CD ripping or flash drive importing is required. And none of that file format incompatibility nonsense either – FLAC and iTunes don’t (easily) come together. Let’s relocate these pluses to audio shows where, rival DAC manufacturers aside, there exists clear possibility for the Resonessence Labs Invicta/Mirus to become a de facto standard for showroom hosts whose selections are crowd-sourced (to some degree). That’s precisely how Singapore’s DITA Audio played it at the Fujiya Avic Spring headphone festival in May of this year. They’d used the original Invicta extensively when voicing their Answer and Answer (Truth Edition) IEMs and had the very same DAC/head-amp plonked mid-table in Tokyo. There’s clearly some work to be done in getting the message to the visiting public that BYO tunes is as trivial as drag, drop and pocket. Still, the potential remains.

    Resonessence Labs’s Mirus layers points of difference, one on top of the other: 1) an in-built transport that’s par with a more-than-decent music server; 2) off-board HDMI display; 3) a DAC that show there’s more than one supremely satisfying manner in which to implement and voice ESS silicon. This DAC is one that I’ve lived with for almost twelve months and the longest period I’ve thus far committed to a review. That’s three sustained killer blows from one box…a knockout. DAR-KO award.


    Associated Equipment

    • Antidpodes DS
    • Light Harmonic LightSpeed
    • Lumin S1
    • AURALiC Vega
    • AURALiC Taurus MKII
    • Mr Speakers Alpha Dog
    • Final Audio Design Pandora Hope VI
    • Audeze LCD-X w/ Fazer
    • REDGUM RGi60
    • Wyred4Sound mAMP x 2
    • KEF LS50
    • Zu Soul MKII

    Audition Music

    • Gregory Porter – Liquid Spirit (2013)
    • Lorde – Pure Heroine (2013)
    • Plastikman – EX (2014)
    • Morrissey – Vauxhall and I (1995)
    • Grace Jones – Nightclubbing [24-96 HDTracks] (2014)
    • Elbow – Leaders Of The Free World (2005)

    Further information

    Additional comments: Many of the improvements that made it to the MIRUS have since been cascaded down to a second generation INVICTA. Details are here.  A more in-depth look at the differences between INVICTA and MIRUS can be read here.

    Written by John

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

    Darko.Audio is a member of EISA.

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