This works great at getting MIDI files working in RPG Maker MZ.
For anyone getting a File Not Found error when using the Play ME command, you need to change two lines in rpg_mixer.js: line 1097 needs to be this._meBuffer = this.createBuffer('me/', me.name); and line 1126 needs to be this._bgmBuffer = this.createBuffer('bgm/', this._currentBgm.name);
Both lines are missing a forward slash after the folder name.