I did your changes. What I got working was that the round sounds are sucessfully disabled while the song is played.
However, the background music (mx_wave_1 overwritten with custom csv) keeps playing, even between rounds as they are no more round sounds to stop it. don't know if it makes sense xD
Fact is, when I trigger the song between rounds, the ambient music stops playing correctly. It seems that I can't stop it while it's playing.
But prehaps I could turn down the volume or something ? I don't know...
Btw you had 666 respects, I saved you by adding one ^^
I am using HarryBo21's swapping perk machine prefab (like in moon). The script is designed like so : the perks swap every rounds. But I would like them to swap every 5 rounds.