KSTR
Major Contributor
APx555 makes it kind of easier. But a good and stable(!) audio interface like the Adi-2 Pro, plus a passive notch filter, plus competent software (REW, perhaps some own code for post-processing) any change of harmonics/spuriae etc is easily detected, IMHO.They would need the APx555 to make this kind of analysis. Since they don't, ours is the only place this kind of analysis can happen.