The Rion DA-21 Data Recorder supports the playback of recorded data. The recorder operates silently without any moving parts, and is also able to operate in difficult environments subject to vibration and humidity. A voice memo recording function is included. Visual level indication is provided via a bar graph display. Data recorded by the DA-21 can be displayed and analyzed using the AS-70 Waveform Analysis Software.

The recorder supports use as USB storage (recognized as removable disk). Inter-unit synchronization allows up to 8 channels maximum. Quantization up to 24-bit is supported. Additional features include a rotary signal input (dedicated connector) and separate input and playback output connectors. A time trigger function is also included.

Battery life is 8 hours using four IEC R6 (size AA) alkaline batteries (20kHz, 4ch, CCLD OFF), or 30 hours using battery pack BP-21A with four IEC R20 (size D) alkaline batteries depending on recording settings.