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In the power supply there are 12 x Nichicon 2.200uF 35V capacitors and 6 x Linear LT1965 regulators.

"In the user manual we do mention that the analog output stage uses jfets. We do however not use discrete jfets but instead the AD797 op-amp as a jfet input amplifier with a DC-bootstrapped compensation capacitor and additional AC-coupled feedback path. While ADI's circuit diagram indicates bipolar input devices, those are not conventional bipolars as can be inferred from the data sheet where collector current and base current are mentioned in a ratio higher than any any reasonable bipolar device can do. We know this through a personal relationship with the AD797's designer. Hence we refer to jfets in the input stage of the AD797.

"Our volume control is digital. This will disappoint those who are aware that the perceived S/N of any musical element is proportional to peak amplitude. An analog volume control brings down the peak signal and noise simultaneously to preserve S/N down to low output levels.

"So why did we go digital? Most of the noise we deal with is actually quantization noise of the signal itself, not noise of the Invicta. For example if we play a CD through a good DAC that performs at a 104dB S/N level we get the results of this table. We see that the analog volume control performs better as soon as we reach -10dB of attenuation. At -40dB the digital control is inferior by a whopping 32dB. That's why knowledgeable audiophiles always ask how specific digital volume controls are implemented.
16-bit CD Analog Digital
0 96 96
-5 96 96
-10 96 94
-15 96 89
-20 96 84
-25 96 79
-30 96 74
-35 96 69
-40 96 64
-45 91 59
-50 86 54
-55 81 49
-60 76 44

16-bit CD Analog Digital
0 96 96
-5 96 96
-10 96 96
-15 96 96
-20 96 96
-25 96 96
-30 96 96
-35 96 96
-40 96 92
-45 91 87
-50 86 82
-55 81 77
-60 76 72
"Our digital volume control performs significantly different due to its higher S/N ratio as the table for the Invicta with its -132dB S/N ratio shows. Our digital solution performs identical to an analog equivalent down to -40dB. Thereafter ours trails by at the most 4dB. There is no doubt that the analog volume control is better. The difficulty of preserving the very low noise and distortion through the analog control was simply not judged worthwhile because the first difference of any kind occurs at the -40dB threshold and that difference is small.

"Now one might wonder about 24-bit data. Below is the corresponding table with realistic assumptions. The salient question to bear in mind is, "what noise gets injected past the analog volume control?" In this table I have used -136dB because this is about what we measure when our DAC is removed from the output path and only the output amplifier and XLR driver are included.

"The analog volume control cannot maintain 132dB of performance because output noise past the control is limited to minus 136dB relative to full scale. Even so it does again exceed the digital control by a small 4dB offset. Note that this table assumes that the noise in the encoded 24 bits is perfect. Any real source will have about 120dB of S/N due to the ADC used in the recording studio.

"The bottom line is, there is no doubt that one would ideally use an analog volume control. We chose not to because in the Invicta the benefits are not as profound as one might assume; and because we judged the difficulty of maintaining reliability, noise and distortion performance with an analog control greater than the benefits."

As Mark Mallinson's original email affirmed, Resonessence's user manual goes to unusual lengths to demonstrate how the Invicta performs on the test bench. Core specs include -110dB distortion and noise and better than 125dB A-weighted dynamic range. These and many other parameters are comprehensively shown with a range of measurements accompanied by lucid explanations about their meaning. Refer to this 70-page manual PDF for all the details [jitter test on 11.025kHz signal as sample below].

Back to analog, the 5.25Vrms max output voltage for each of the 6.3mm 30Ω headphone sockets can be trimmed independently with the multi-function master and individual headphone controls. This accounts for offsets in headphone and listener sensitivities. Two people can thus comfortably listen together over the same master volume and do so over very different headphones. Inserting headphones does not mute the main 75Ω RCA and 150Ω XLR outputs. The Invicta always passes signal over all its outputs simultaneously.
24-bit data Analog Digital
0 132 132
-5 131 127
-10 126 122
-15 121 117
-20 116 112
-25 111 107
-30 106 102
-35 101 97
-40 96 92
-45 91 87
-50 86 82
-55 81 77
-60 76 72

Output voltage on XLR/RCA vs. readout equals 5/2.5V for zero attenuation, 4/2V for -2, 2/1V for -8, 1/0.5V for -14, 0.5/0.25V for -20 and 0.2/0.1V for -28. The manual volume control proceeds in 0.5dB intervals from -125.5dB to zero.

Back on connectivity there are Toslink i/o ports. The transformer-coupled and thus galvanically isolated active twin 75Ω BNC inputs can be programmed* and the 110Ω AES/EBU input is transformer-coupled as well. The HDMI input accepts DVI audio from video sources. The SD card slot is for Class-10 cards and presently compatible only with WAV files up to 24/192. The 115/230V indicated mains voltage can be swapped by reversing the orientation of the fuse holder. Owners moving residence into a different zone needn't send the unit back for conversion.

* "Every aspect of the Invicta is programmable to some degree. The i/o ports meet or exceed the physical layer specifications so that for example two of the BNCs are programmable as input or output and currently are configured as selectable S/PDIF inputs. If it turns out customers want word sync, clock and data—which we initially considered—then a simple software upgrade will create that. Furthermore the HDMI connector at the hardware level can do I²S over HDMI, HD OSD output, ultimately even HDMI audio. Currently it does none of these because our software team has not yet completed the necessary firmware/software to our satisfaction."

Upon power-up the Invicta automatically sets output to −30dB to avoid nasty surprises. As a high-performance design this machine only accepts uncompressed data. It mutes in the presence of diminished files as though to say "MP3, bad dog!"

"The team of individuals I have assembled include world-class analog and digital engineers who have specialized over the past 5-25 years in the design of integrated audio circuits together with a number of firmware experts. Our team members are passionate about audio design engineering. For myself I have spent the past 16 years involved in one startup or another. My last company sold to ESS Technology in a multi-million dollar deal. I feel that it's time to do it again. Resonessence is self funded. Our goal is to build a successful long-term business based upon bringing the very best of audio engineering to market in the form of system-level products such as Invicta."

Concluding introductions, the Invicta's asking price of $3.995 positions it one layer up from the Burson and Wyred4Sound units reviewed in these pages, on par with my Weiss DAC2 and recently written up Antelope Zodiac Gold + Voltikus and one layer down from the newer Weiss DAC202 where each doubling of price no longer tracks performance increases in linear fashion. Full featured in socketry including that unexpected but brilliant SD card slot whose use eliminates a computer for playback altogether, only a remote wand is missing to add creature comfort for the promoted amp-direct mode. But arguably the Invicta's most unique feature is having been designed by the team behind the ESS Sabre chip. This presumably makes it a no-prisoners proof of concept which mines that chip's fullest potential. Fans—units by Eastern Electric, Calyx, Oppo, Wyred4Sound and Weiss run on Sabre for just a few—might earmark the Invicta as possible it machine in this price class.