To use these D&B Audiotechnik Ci90 loudspeakers, first, find a stable place to set them up. Make sure they are connected properly to your audio source. When playing music, adjust the volume according to your needs. As for the missing grille foam, it won't affect the basic function, but you should be careful not to let dust or small objects get inside the speakers. To keep them in good condition, regularly clean the outside of the speakers with a soft, dry cloth. Avoid exposing them to extreme temperatures or humidity. If you have any other questions about using these speakers, feel free to ask.
