I. Introduction
The nature of the electrical signals that carry audio today is almost exclusively digital in nature, thanks to advantages in technology that allow low-cost signal processing. Even in power amplifiers, whose output must be analog in order to drive the speakers, the digital input is becoming more and more common. Consequently, also in power audio technologies it is increasingly common to have high-performance digital parts together with analog parts, with the latter benefiting of fewer advantages from the reduction of lithography, which instead makes the digital parts more performing and cheap.