Using Class A operation in all stages, the SU-A2 was completely free of switching and crossover distortion, and realised low distortion and a high S/N ratio. Featuring the DC amp structure, the SU-A2 used no capacitors and achieved faithful waveform transmission. From the Phono MM input to the output terminals, the rated distortion factor was 0.003% in the range of 20 Hz to 20 kHz (at 1-V output). The SU-A2 was provided with a low-noise dual FET for MM and a newly developed low-noise transistor for the MC preamp. Use of the active thermal servo amp minimised DC drift. Despite the multi-functionality, the simplified wiring and switches in each section offered minimal crosstalk. The universal frequency equaliser was configured with four elements in each channel for a total of eight elements. The SU-A2 was highlighted as the most advanced, top-level control amp of the day.