I mute the music and turn everything else down. Unless it has decent voicing (which very few do.) I usually turn the sex sounds way down as they tend to be generic shit.
I used to leave it as it is in the past, but I play more western VNs nowadays and turn it off. I generally just play my own music, the only time I care for game music is when I played Quartett!, but it is a VN that has a focus on it, so it makes sense.
If there's a sound, I always leave it on. After all, that's the creator's intention, and it suits the game better. I don't like when separate sounds are created for the voice, sounds, and music on the same control scale, even though Renpy has a default function for that
sound always off, 90% of the time all you're missing is really loud royalty free music and then random moan sound thrown in depending on the game, detracts way more than it adds