I'm wondering if your allowed to replace music files & still have your run verified just like SADX. Could anyone let me know.

assuming you are running the pc release, then yeah you can modify the adx's (you can even delete the music adx's and just play your own playlist too)

Thank you for letting me know. I just recently got the steam version but I haven't seen any runs of the game yet. I'm still gonna do SADX runs but I might try SA2 runs in the future.

Yeah you're allowed to replace music files. Assuming you're playing on PC, go to the games Local Files->gd_PC->adx. The Music files are that folder, formatted under an ADX format. Sound effect customization aren't allowed