Hi there, I do not follow that thread but if anyone interested in the root cause of that "hump" phenomenon I have to show something. The attached plot is power sweep vs THD+N my tiny ES9038Q2M USB->DAC->HPA dongle on real planar headphones loaded Fs=44.1kHz 24b. 100MHz named curve correspond reg#0 value 2’b00: MCLK = XI (default), 25MHz at 2’b11: MCLK = XI / 8. As you can see the blue 100MHz curve has no hump at all, and you can ask me why some DACs uses lower MLCK value? Check this out(note: FFT after 40db notch), harmonics distortions
distribution is quite different for 100MHz vs 25MHz, however THD+N very close for both modes. 25MHz mode has nearly perfect harmonics set - 2, 3, 5.. and nothing more, then 100MHz has lot's of small nails at 15, 17 and 19khz. I made some buttonless "easter eggs" hidden interface for my #9038S USB->DAC->HPA dongle to let user switch between 3 modes:
1) Normal-mode 100MHz
2) Performance-mode 25MHz
3) SE-mode 100MHz+.25% of 2nd harmonic
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