It looks like an overly simply music player, and that's because it is. The settings here actually apply to the project, so you can configure the start and looping time of each song, then test the song. These settings get saved automatically, so there is no APPLY button. I've noticed lots of the MIDI files from the old RPG Maker 2003 resources have silence at the beginning of them, so the start position comes in handy here. You could then set the loop time to the same as the start time (shown above), or make it 0 for there to be a moment of silence between each loop. As for the panning, speed, and volume settings you were expecting, those only appear when assigning songs to things (event scripts, map settings, etc.). There will be a preview button so you can test the sound settings out before deciding upon them. Music files are simply added to the .2xg file as-is, so be careful about compression. The editor won't accept raw WAVs as music tracks for this reason. If you need lossless audio, convert to FLAC instead and then import. Nobody wants to download 500+MB of soundtrack data just to play a classic 2D RPG.