The new staple for this price range, features a newly designed driver unit [f-Core DU] which realizes astonishingly clear sound. For the A4000 to achieve the impossibly high-quality sound for this price range requires new development and production facility. The 6mm diameter dynamic driver requires not just new parts, but a total redesign of everything, including the production machinery. Sound design was conducted based on proprietary sound evaluation method established during the development of flagship A8000 model. It achieves “transparent sound”, which means an impression that even sound images localized distantly can be heard clearly, for various genres of music.