PolemiGD t1_jd68ryt wrote on March 22, 2023 at 3:04 AM

There are a lot of variables here but it probably is just an error of how fourier transform is used in the application. Still there could be more problems with the dac and/ or method of EQ. There are many ways of making digital EQ filters.

Acceptable-Exit-9212 OP t1_jd6z9qb wrote on March 22, 2023 at 8:16 AM

I tried many different audio sources etc. and the problem persists. So, the issue is tied with the DAC. Typically such EQs are implemented with IIRs. My quess is that they are using something like CM6533 . Samplerate matching control loop could cause this. (I don't think there is FT anywhere in this part of chain.)