E30 RCA out vs d30 Pro RCA out at 3khz showed no difference around 3Khz. They overlapped each other.
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X16 RCA out vs d30Pro RCA out continue to show difference for 3khz. Blue is x16.
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Note that I have done many more comparisons yesterday using XLR out of d30pro and X16. The fundamentals matched very well for 1khz, 1.5khz, 2khz, 2.6khz, 3.2khz, 4khz, and 5khz. The only differences I noticed were 3khz. Strange.....
Anyway, if you think of anything else to measure to show differences in perception of "clean" sound, let me know. Thx!