Doom: Eternal would not feel like a good Doom game if it didn’t have an amazing soundtrack. Not only does the game feature a variety of original songs, but you can gather up other albums scattered throughout the game as secrets. On the xxx level, you can find a single album, which is the first one you can find in the game.
You have access to obtaining the album after you have gone through the portal in Exultia too Hell and acquired the plasma rifle. After you kill a wave of enemies, you need to clear a path using a sentinel battery to power a downed mech’s arm to blast your way through the next section. Before you advance through the level, stop, and turn to the left of the downed mech’s arm.
There is a significantly large block preventing access to a lower area. Go to the side of it, and punch it on the side with glowing green symbols. Proceed down the previously hidden path, and at the end you should find your first secret album you can listen to in the game.
There are 16 albums hidden in Doom: Eternal. Make sure to keep your eyes open to find all of them.