Just as the standard ZeroUno, this orange-on-black display of the Pure is ultra informative about your input settings. It can also just show volume in bigger numbers. The rotary Elma encoder handles volume and menu navigation. On the back sits a quad cluster of digital inputs and a matching set of analog outputs. Of those one pair is variable to accommodate minimalist amp-direct scenarios. Now Sabre's on-chip 32-bit digital attenuator handles SPL. The other pair is fixed so bypasses the digital volume. That will be followed by a preamp or integrated's analog volume. Optionally, one of these outputs can be true balanced XLR. Max voltage swing is 9Vpp or 3.2Vrms

Mario's machines tend to be heavy for their size and use thick-walled chassis nicely lacquered. They also use 4-layer boards, an XMOS XU216-512 USB transceiver with 16 CPU cores and 1-Farad supercap power buffer and smart protection circuitry which launches auto diagnostics with each power cycle before going active. While that delays things by just a few seconds, it does give peace of mind that everything operates as it should. As you just saw, the amenities even include balance control and polarity inversion. By July 13th, "the Pure DAC is 90% ready, debugged, fully assembled and has been playing solid for a week. It only missed the front plate which the paint factory promised for tomorrow so I can deliver next Monday." Show on the road. Sunshine in overcast Ireland?

"Although the Sabre32 chip set is very powerful, it arrives from the factory documented for only its standard configuration. This won't show ultimate performance. To make full use of the complete feature set needs advanced engineering. We wrote complex firmware to run this chip at full potential. The core implementation is as two-channel DAC based on four paralleled pairs of differential converters. The high-quality 32-bit on-chip volume control guaranties optimum channel separation and balance even at very low levels. The patented internal jitter reduction module drops jitter to very low levels. But the real brain of this converter is the firmware written for it. Our special internal configuration eliminates the type distortion which more or less was part of digital audio since the inception of CD in the early 80s. We developed the ZeroUno Pure mainly to avoid it. Our custom firmware stores on a separate memory chip fitted in a socket on the board. This also creates a future upgrade path via firmware updates.

"Our power supply is based on three toroidal power transformers for the digital, analog and control-logic sections. All transformers sit in anti-magnetic metal canisters potted with resin. The supplies for analog and digital circuits split into two sections. The first pre-regulates the DC voltages and isolates the second section from the AC mains which now works in 'quasi' battery mode across 13 ultra low-noise feeds. Four of these consist of exclusively discrete components for maximum noise reduction. Almost 60% of our R&D time went to this PSU. Four elite AD797 opamps commonly seen in output stages feature in four of the 'first-level' supplies. Rather than electrolytics, almost all our power-supply capacitors are aluminium organic solid polymer types and we add 13 individual coupling inductors for further noise filtering.

"In many products, multiple printed circuit boards connect via flying leads. The higher a circuit's signal frequencies, the higher the potential for negative influence by electromagnetic induction from hookup wiring. DACs will process digital input signals up to 20MHz where electromagnetic induction can become a nightmare for the engineer. The same is true for correct grounding of all circuit modules. To avoid these common issues, the ZeroUno Pure consists of just one four-layer PCB with extra-thick copper traces. This means ultra-short signal paths with minimal wiring. Extra layers are reserved for the ground planes and power lines of each stage."

This is the perfect junction in the narrative to invoke hifi hookworms. To paraphrase, power supply, analog output stage and I/V conversion are all segments in a DAC which make a big difference, arguably more so than the choice of converter chip. As Mario explained, to this we must add custom firmware controlling the chip; and that relative to final sonics, the power supply is probably most important. All Sabre DACs sound the same? Hardly.