Quote Originally Posted by JanVana View Post
Hello Clive,

I have a Raspberry 4, Amp100 and a DSP module running. I have the same issue with low frequency rumble on some Hifiberry DSP Profiles. I asked hifiberry for support, but unfortunately they can't help me. Have you found a solution.

Thanks for your help. Regards.
Jan, I saw your post on the HiFiBerry forum and responded there.
But to summarise: ditch the DSP card and just use SOX to apply the filters you need.

I strongly suspect that the algorithms used in the DSP card are flawed.