I haven't tried using a ceramic coating, but I'm having a problem grasping the concept of a liquid ceramic. I have heard that some are difficult to remove, though. I would be inclined to contact the manufacturer to find out exactly what was used as a finishing material, to prevent damaging it by using something that could affect it. If they used some kind of catalyzed lacquer, I doubt much is needed and if necessary, it could probably be polished. DO NOT use anything with Silicone, or it will be very difficult to repair the finish on the speaker(s) and anything nearby when the Silicone was released into the air.