I bought a second hand M-DAC to have a well-known commercial reference in terms of measurements and sound. Obviously I needed to open it and see what’s inside. This is not a detailed reverse-engineering report but a glance inside with plenty of photos. Measurements are coming later.
- LM4562 and NE5532 show almost identical performance in I/V stage, while OPA2134 is 2 dB weaker.
- LM4562 is the best performer in differential amplifier.
- The best solution is to use NE5532 in I/V-stage and LM4562 in differential amplifier as it gives almost identical performance to all-LM4562 implementation
- Differences in distortion are mostly due to odd left/right channel differences of PCM1794A.