E1DA Cosmos APU - Teardown and personal thoughts and measurements

[pkane]

right, it happens due to the high impedance of the notch at the rejection frequency. But it's not a reason to worry about, APU's notch limit for THD+N is around -135db i.e. something like 3x times lower vs APx555.

This looks good to me, although noise appears to be close to that -135dB line and I can still see the tilt of the noise floor

 

[IVX]

I did explain my result here https://www.diyaudio.com/community/...perform-apx555b-for-30000.386001/post-7063707
In fact, I didn't see the THD+N <-132db@1kHz@10Vrms with my Cosmos DAC proto(DAC+LPF output).