I use Coax and RCA out, and they are affected for sure. I haven't tested optical, but I don't see any reason to why it should not work, when the other outputs does. But I can try to dig out an optical cable if you would like to know.Thank you. That is really interesting and basically changes the game. Perhaps we can request to @FiiO that they store PEQ settings for each of the Output settings and have the R7/R9 switch the PEQ automatically as different Outputs are selected.
It would be useful to have it confirmed that the PEQ does indeed apply to optical/coax/ USB as well as the apps.
I have tested Tidal, Qubuz, Bandcamp and Plex, and all these apps are also affected by the PEQ changes.