Marco Serri's main objective in designing this converter was to create a digital equipment capable of flawlessly emulating analog sound. The equipment consists of two chassis: one dedicated to power supplies and the other containing the necessary electronic chips for operation. Both chassis are made of anodized aluminum with a thick front panel housing a large digital display that shows the operating mode and sampling frequency used.
To emulate analog sound, two Sabre 9038 Pro chips were used in a dual mono configuration. This setup allows the two chips to work in parallel, doubling the signal and improving channel separation for maximum stereo separation and a highly linear signal. This operating mode ensures better signal quality and eliminates typical mechanical artifacts of digital signals, leading to significant listening benefits.
Particular attention was given to the selection of components for the filtering and output stages, which were treated with the same care as in the creation of a high-end valve preamplifier's output stage, with separate power supplies. Rather than focusing on the power of the chips, emphasis was placed on the care of the filtering and output stages to enhance the DAC's sound quality. This resulted in an excellent outcome with the use of 5 Euterpe Audio transformers by Crio Marzio, a renowned craftsman who manually crafts high-quality transformers and inductors. These transformers are built with special winding geometries and double "C" cores sourced from supplies of similar quality to military-grade components. High-purity copper wires with a purity level of 99.998% are used in their construction.
Instead of using a single transformer with multiple secondaries to power each circuit, as mentioned above, five transformers were employed. Specifically, there is one power transformer for the anode valve, another for the valve filaments, one for the rectifier valve filaments, one for digital section 1, and a fifth one for digital section 2.
For valve power supply, a rectifier valve was chosen, avoiding the common silicon diode bridge that could compromise the purity of valve sound. Additionally, a double Pi filter configuration was used, contributing to the signal quality improvement.
Four 6NS7 valves and one rectifier valve were carefully selected to achieve the highest possible sonic performance.
The listening experience with this equipment is simply astounding, thanks to its explosive dynamics, sonic depth, focus, and transparency. The immediate sensation is that of immersing oneself in a music piece reproduced by an analog turntable, with the extraordinary addition of all the sonic qualities of digital, such as complete background silence and the ability to reproduce incredibly engaging dynamics.