With the UA4, all the favorite features of the previous UA models have been combined, adding a brand new ESS DAC. It has a 0.87-inch display that provides information about the current playback and quick access to settings. It features three buttons that allow control of playback and volume.

The audio circuit uses dual Ricore RT6863 headphone amplifiers for balanced output and an output power of up to 211 mW @ 32 Ω. It includes an ES9069Q DAC from the latest generation of ESS DACs, with a focus on clean and noise-free output for high-performance headphone users.