Resonessence Labs INVICTA Mirus DAC
Input: Asynchronous USB 2.0, SD/SDHC/SDXC cards. The USB supports up to 24 bit/ 384kHz as well as DSD64 and DSD128. The Card supports 24-bit / 384kHz for WAV and AIFF, FLAC is 24/192k. AES/EBU (S/PDIF) and 2 BNC (S/PDIF) inputs are included that support up to 24/192 kHz. A Toslink (S/PDIF) is also included.
Output: (1) Pair Unbalanced (RCA) and 1 pair XLR. An HDMI Output is included for reading the directory structure of any of the card formats with an HDMI connected monitor. A Toslink output for the SD card data.
Dimensions: 8.66" wide by 11.10" deep, by 1.97" high
Weight: 6.4 pounds
Availability: Authorized Dealers and Direct On-Line sales
The Resonessence Labs INVICTA Mirus DAC represents the state-of-the-art offering from this Canadian company. The Mirus is closely related to the Invicta DAC that Michael Lavorgna reviewed in May 2013 (see review). Michael presented an excellent review that was quite thorough in describing the features of the Invicta. Since that time, a number of improvements have been added to the Invicta, including a new model called the Mirus. The XLR/RCA output specifications of the INVICTA Mirus outperform those of the standard Invicta. The headphone module is removed in the Mirus, and replaced with a second ESS Sabre DAC ES9018 for each channel. By combing 2 ESS Sabre ES9018 DACS in parallel per channel, a total of 8 ES9018 channels are available for each stereo output. Resonessence Labs has discovered that every time the Sabre DAC output channels are paralleled together performance improves. This feature results in a lowering of the noise and a decrease in THD compared to the Invicta. The dynamic range specification is also improved in the Mirus.
It should come as no surprise that the Mirus utilizes the ESS Sabre DAC. Mark Mallinson, the founder of the company and President of Resonessence Labs, was former Operations Director for ESS Technology. Mark brought together a team of design engineers that were involved in the design of the ESS Audio DAC and ADC allowing them to get the highest level of performance from the ESS Sabre DAC.
- Dual ESS Sabre ES9018 DACs per channel
- Unlike many other manufacturers, the USB interface code is Resonessence Lab’s own. The Windows drivers are provided by Thesycon.
- A digital volume control with the necessary range to successfully drive amps directly.
- Analog Devices AD/797 op amps in the analog circuits. While the use of this op amp is somewhat controversial for a high end DAC, Resonessence Labs has found that this op-amp is a high linearity open loop design that has the benefit of matched, complementary, on chip, bipolar devices. Resonessence Labs selected this design as it yielded the best sound for their DACs. A detailed explanation of this design can be found at the FAQ at their website.
- Galvanic isolation of ground noise using multiple power supplies as well as separate grounds with a separate power supply for the digital section. With galvanic isolation, the audio system ground is not disturbed by the USB flow control artifact. Phase noise modulation with power supply variation is also kept to a minimum.
- Resonessence utilizes the jitter rejection aspect of the Sabre DAC (activating its Asynchronous Sample Rate Convertor and Jitter Removal Circuits) This results in a further up-sampling to the precision master clock rate, which in all Resonessence products is an ultra-low jitter fixed-frequency 50Mhz CCHD-950 clock.
- DSD over PCM (DoP) for playback of dsf and dff files via USB and S/PDIF
- 7 selectable filters that can be changed while music is playing. 2 of the filters are the pre-programmed filters found in the ESS Sabre DAC. The other 5 were designed based on user feedback.
- An Apple remote is included with the Mirus.
- An elaborate front panel display that allows various user configuration settings and display of volume settings. An LED display is also provided to indicate sample rate and DSD playback.
I asked Resonessence Labs to provide additional information on their power supply and clock designs. The following was provided by the lead designer of the Invicta / Mirus:
- We use a low noise toroid to start with that we spent a lot of time with the supplier defining the spec. Even their “Medical Grade” ones were too noisy; we actually even helped them on the construction of their toroids to get the stray magnetic field down.
- The Mirus has 3 fully isolated supplies the come off the secondary's of that toroid, 1 for the digital section and 2 for the analog section.
- The 3 supplies then have an R-L-C filter on it to prevent noise from coupling for the digital supplies back the analog supplies through the transformer.
- For the Digital section, we have low noise LDO’s (LT1965) used for every voltage reference. These voltages power up everything in the digital section of the INVICTA.
- For the Analog section, the 2 supplies are used to create +9V and –9V references, again using the LT1965 LDO.
- The Analog and Digital section are 100% galvanically isolated. To do this, one MUST use something like the ADUM1400 in order to get the grounds to be fully floating. This eliminates any changes of ground loops.
- The power supply for the clock is its own. It's an ultralow noise custom design that has been tailored to the CCHD-950 running at 50MHz.
To compare how our clock stacks up against a “Femto Clock”, refer to the phase noise plots as this is what matters for Audio. Specifically the 10Hz to 100kHz numbers.
- For the rest of the clocking, we actually put the clock in the analog section, and send the signal to the DAC so that it gets the lowest possible phase noise reference clock possible. Then we buffer that clock signal and send it back to the digital section of the PCB through an ADUM1100 isolator.
- Doing this slaves the digital FPGA section to a clock that is used for the DAC. We did this so we could implement our own up-sampling algorithms we believe to offer superior Audio performance than the stock Sabre Filters.
I think I can say that for Audio purposes, the clock we chose is superior based on this metric, which we at RLabs personally believe best correlated with sound quality.Associated Components Used in This Evaluation
The Design of the Mirus Case
The casework of the Mirus is very impressive by anyone’s standard. The front panel and chassis base are CNC machined from solid 6061 T6 aluminum. The fit and finish of the product is precise and quite exemplary in its appearance. I have no doubt that this level of precision of the case reduces internal component vibration as well as providing a precision feel to use of the switches.
An early 2011 MacBook Pro 2.3 GHz, 16 GB RAM with Samsung SSD was used with 2 GRAID Thunderbolt drives for the music libraries; one for PCM and the other for DSD files. OSX Yosemite and Boot Camp Windows 8.1 64 Pro were the operating systems. I used Audirvana 2.09 and Pure Music 2.04 with OSX Yosemite. JRiver Media 20 with Fidelia Pro 6.5 were used in the Windows evaluations.
Most of my listening was done with Pure Music 2.04. Pure Music sounded magnificent with the Mirus and made an ideal match sonically for this DAC. The program was rock solid in performance with the latest iTunes version and the Remote iPad app.
The GRAID Thunderbolt drives were powered by HDPlex linear power supplies. An iFi Micro iUSBPower was also driven with an HDPlex linear power supply. The Mirus was listened to with the USB cable directly plugged into the MacBook Pro and also connected to the iFi Micro iUSBPower.
One component that has made a big difference in the performance of my system is the Shunyata Research Hydra DPC-6 power center. The MacBook Pro and the hard drives were plugged into the DPC-6. The iFi Micro iUSBPower and the Mirus were plugged into a Shunyata Research Triton power center.
The computer and the DAC were each placed on Synergistic Research Tranquility Bases powered by their Transporter Ultra SE. Synergistic Research Thunderbolt Active SE cables were used for the hard drives. The USB cables used in this review were the Synergistic Research Galileo LE, along with the JCAT Reference USB cable, and the Shunyata Research Venom USB cable.
As I listened to the Mirus over several weeks, I was very impressed with the sound of this DAC. The general sound of the Mirus is basically relaxed with no hardness or thinness to the sound. Music emerges from a very black quiet background with excellent definition and focus. Both micro and macro dynamic changes are reproduced well with no blurring of detail. The DAC is fast sounding with excellent control of the bass. The soundstage from this DAC is wide with good depth reproduction. Listening with Pure Music 2.04 resulted in a layered soundstage with air and bloom around the instruments when listening to well recorded orchestral music. I found the Mirus to be non-fatiguing and easy to listen to for extended periods.
I enjoyed listening to Vladimir Ashkenazy, London Symphony Orchestra conducted by André Previn performing the Rachmaninov Piano Concertos (24/96). The acoustic space of the venue was well reproduced with a feeling of air around the instruments. The Mirus did a wonderful job in reproducing crescendos with no compression of the sound or hardness. The focus and definition of the piano was also excellent with great body and solidity to this instrument.
The Mirus did an equally fine job playing Rhiannon Giddens’ solo debut album Tomorrow Is My Turn (24/96). While well known for folk music, Rhiannon’s album offers a variety of music from folk to gospel to country. The Mirus beautifully reproduced her strong voice with multiple shadings and liquidity.
The Mirus has very capable bass response that can deliver terrific impact and slam into the room. REM’s New Adventures in HiFi 24/48 was reproduced with a truly visceral grip of the bass that was rhythmic and exciting to listen to.
Neil Young’s After the Gold Rush (24/192 Pono) was extremely rich and musical sounding on the Mirus. There was a tonal naturalness that I did not hear from my CD rip of this title that allowed me to relax and enjoy the music. Neil’s voice was clear and focused with a tube-like bloom and dimensionality.
The DSD performance of the Mirus was every bit as good as its PCM playback qualities. I found the Mirus to be equally comfortable with PCM and DSD titles with never an issue moving from one format to the other. The special midrange qualities of DSD emerged with the excellent soundstage qualities heard in PCM playback.
I thoroughly enjoyed listening to the DSD Stockfisch recording of David Munyon’s Pretty Blue (dsf). A rich, relaxed midrange was heard with image solidity of David’s voice. The delicate and nuanced sound of this recording was well reproduced by the Mirus.
I found the 7 selectable up-sampling filters to be a highly desirable feature of the Mirus. While 2 of the filters are provided with the ESS Sabre DAC chio, the other 5 are custom designed by Resonessence Labs.
The custom filters are:
- Minimum Phase IIR Filter
- Minimum Phase Slow Roll-off
- Linear Phase Apodizing Filter
- Linear Phase Fast Roll-off
- Linear Phase Slow Roll-off
The Digital Volume Control
The Digital Volume Control of the Mirus is done in the 32-bit domain. Given its fine gradations, it should mate well with most power amps for those that prefer to not use a preamp. I found the general sound of the Mirus directly connected to my Ayre MX-R amps to be very satisfying, but eclipsed by the use of the Ayre KX-R preamp in terms of ultimate sound quality.
The SD Card
I found the SD Card feature to be very useful for not only its sound quality, but assessing the sound of one’s computer system. Mark Mallinson told me that the operating system utilized for the SD Card is a custom operating system that is bare bones for audio. Resonessence Labs wrote the SD Card hardware controller that is implemented in the FPGA.
From Mark Mallinson:
“I'm not aware of any other company that has done this before for Audio; usually it’s a general purpose CPU with a Linux variant on it. We went all the way by first writing the hardware blocks that are put into the FPGA, then the driver that allows the software to interface to it, then the software to talk to the driver to make it do useful things such as play music.”Mark felt that the SD Card playback was the cleanest way to get audio files to the DAC. What was also very interesting to me was the claim by Resonessence Labs that with the firmware Release 3 for the Mirus, that the sound of the SD Card and USB was indistinguishable. The SD Card feature supports files in WAV, AIFF, FLAC, DSF, and the DFF formats up to 24/ 384 kHz and DSD 64 / 128.
I placed a variety of AIFF files on my SD Card up to 24/192 and a number of DSD 64 files for evaluation. The built-in navigation feature of the Mirus is easy to use with the directories and titles being displayed on the front panel. One can also connect a monitor to the HDMI output for display of the SD Directory.
I thoroughly enjoyed listening to music from the SD Card; after all, this is about as pure a form of playback as one could hope for. I then compared the sound listening to the same files from my computer using Pure Music 2.04. To my surprise, there was only a slight difference in sound between the SD Card and computer playback. I found the bass to be slightly fuller sounding when listening to files played from the computer. Moving the USB cable directly from the computer to the HDPlex / iFi Micro iUSBPower made no difference. Changing USB cables did not seem to make much of a difference either in the sound of the bass.
I found this to be a truly remarkable finding as it demonstrates just how good the isolation of the Mirus is from the second order effects produced by computers, USB cables, etc. This is an accomplishment that very few DACs I have tested have been able to achieve.
I Could Happily Live With the Mirus
I think the highest compliment I can pay to the INVICTA Mirus is that this is one DAC I could happily live with. It is basically an uncolored, highly dynamic, and easy-to-listen to DAC that was always musically engaging in its presentation. The galvanic isolation found in the Mirus results in sound, that when using a computer, is very close to the sound obtained with the built-in SD card source. This feature will allow anyone to easily compare the sound of their computer set-up with the Mirus’ dedicated custom operating system. Is the Mirus the finest DAC I have ever heard? Some of the significantly more expensive designs I have reviewed are even more analog-like in sound quality. But I never felt that I was missing anything sound-wise when listening to the Mirus. In conclusion, the Resonessence Labs INVICTA Mirus is one fine DAC that I highly recommend.