Delta sigma DACs are today’s standard for digital processors. Not because they provide better audio quality, but because of availability and ease of implementation of digital filters. Filters that became more and more complex, only because of the artifacts created with delta sigma modulation. The Kassandra’s prototype was developed very early, not as a commercially available design, but as a cost no object lab tool, my personal reference tool for speaker and amplifier development. The decision to put it in production and to be commercially available was decided at a much later stage.
We found since then, with many new converters launched daily with impressive specs. on paper, that they fell short of what we call analogue sound. They always presented that electronic signature that gives digital reproduction a bad name. The ladder DAC (R2R) is a resistor network switched by an N number of switches, N being the bit depth. It is a passive sort of speak procedure, whereas delta sigma (DS) technology, while still developing and moving forward, is a completely different kind of conversion procedure.
Creating an analogue signal from noise shaping (as in DS conversion) sounds counter intuitive. The very complex, very high order filters implemented to reconstruct the analog signal do create very good specifications on paper. However the high complexity of the filters and resultant very high energy (several KHz-MHz noise present) is what gives all DS converters their distinctive sonic signature, a sonic attribute often given the term ‘digital sound’.
