Six years ago Alpine made the proposition that ultrasonic components were important to audio reproduction. The implementation of our proposal was the DA-07, a unique D to A converter employing a new interpolation program. Since then we have continued to study the impact of ultrasonics. We introduced a D to A converter unit for car audio (model 3900), which employed this technology. But, it did not penetrate widely because of its size and cost. Success required integration. The new one-chip Fluency DAC (FEDAC) incorporates D/A conversion and DSP to fully implement the “Fluency” interpolation method without loss of audio performance. This paper describes the theory of Fluency interpolation, the history of integration, and the performance evaluation of the one-chip Fluency DAC.