Are the speakers for the 50S compatible with the clamp kit for the 30K, 20S or 20S EVO?

Yes, the speakers for the 50S are compatible with the clamp kit for the 30K, 20S, and 20S EVO. However, the speakers on the clamp kit for the 50S will provide louder, clearer and better bass audio when used with the 50S main unit and the 50S clamp kit and will not provide the same high quality audio when connected to the main unit and clamp kit for the 30K, 20S, and 20S EVO.