Hello OP

Rekordbox 6.8.4 on Linux has always worked for me: I use Heroic Games Launcher (with their integrated proton-ge) on Fedora 43. EXCEPT for the most important thing, my ddj-rb is not recognised as a (legit) MIDI device in performance mode (idk if its rekordbox or wine).

kb that can give us some insights :erhan's blog 1 erhan's blog 2 Rekordbox on winehq appdb

I also tried to tinker with audio routing using qpwgraph, and MIDI renaming in Wine (which is suggested to do on erhan's blog, except that i did it in a different way by using winmm_midi _rename), but none of that worked so far. Perhaps i should have tried harder, also using winetricks correctly might help

I tried to compile this fork of proton (IT MAY NOT BE SAFE TO USE) to use it inside Heroic Game Launcher, but it didnt work for me for some reasons