The Erebus mod features its own 2 music tracks that are only heard in the Erebus dimension. When you are walking around in the Erebus and have your music off, Turn it on and wait around 15-30 seconds or a few minutes and music should start playing. As previously mentioned there are 2 different music tracks that are heard only in the Erebus. Unfortunately I don't know a way to get the music file on here for listening without uploading a video, and plus most Media Players built into computers don't support the file type: .ogg (Erebus music files)