My Cosmos ADC is A-grade and set to 3.5 Vrms. All RMAA measurements are 24/192KHz.
TLDR: The THD performance of DX7 Pro+ is great at -1.0dBFS but worse at -1.2dBFS. All ESS DACs have this "oscillating THD" issue (see https://archimago.blogspot.com/2022/07/hi-res-thdn-vs-output-level.html)...
So I bought DX7 Pro+ out of curiosity and measured it using Cosmos ADC (grade A).
Note: Here Cosmos ADC is in stereo mode so the noise is not the best. But I care more about harmonic distortions :) My Cosmos APU will arrive tomorrow and then I will measure them again.
THD of DX7 Pro+:
THD of...