protontricks 628060 -f quartz devenum wmp11

In addition to nanliu's report below and the protontricks mentioned here, you also need to alter the codec used by the BGM so they can play correctly.

under Steam/steamapps/common/San10WPK/BGM/, create a text file and name it fix_audio.sh. Open the file with a text editor and copy and paste the following into the file:

#!/usr/bin/env bash

for wma_file in *.wma
do
    new_filename="$wma_file".ORIGINAL
    echo "Renaming $wma_file to $new_filename"
    mv "$wma_file" "$new_filename"

    ffmpeg -i "$new_filename" -acodec pcm_s16le "$wma_file"
done

Open up a terminal in the BGM directory and run the following:

sudo chmod +x fix_audio.sh
./fix_videos.sh

This should allow the BGM to play properly.

Also under Steam/steamapps/common/San10WPK/, I would highly suggest to just rename the Movie folder to something like Movie_bak so the game doesn't try to play the movies.