This application bulletin will provide the reader with an understanding of test methods for audio digital-to-analog converters (DACs). In particular, delta-sigma (∆Σ) DACs require a special understanding due to the nature of their architecture. The dynamic specifications of interest for an audio DAC are THD+N (total harmonic distortion + noise), dynamic range, channel separation, and idle channel noise (often referred to as SNR, signal-to-noise ratio). There are many possible digital audio applications, but only CD-DA (reproduction of digital audio from a compact disc) has a standard specification defined by EIAJ (Electronic Industry Association of Japan). Test methods for evaluating DACs used in other digital audio applications are somewhat am- biguous. For these applications, evaluating the DAC is highly dependent upon the experience and knowledge base of the design engineer. Digital audio reproduction is based upon sampling and Nyquist theorems. This application bul- letin will describe the operation theory of ∆Σ audio DACs, and associated test methods for these DACs.