Composer
Extraction
Umodel / UE Viewer
C:\Program Files (x86)\Steam\steamapps\common\Sanctum2\SanctumGame\CookedPC\Sound
See spreadsheet for which ones you need
Also look in these directories for DLC music not included in the main folder:
C:\Program Files (x86)\Steam\steamapps\common\Sanctum2\SanctumGame\CookedPC\DLC2\Sound
C:\Program Files (x86)\Steam\steamapps\common\Sanctum2\SanctumGame\CookedPC\DLC4\Sound