In addition, iTunes DRM protected music is M4P format and the non-protected music is M4A format. Some devices do not support it. Therefore, if you want to play iTunes protected music properly on your devices, you need to remove DRM from iTunes music and convert it to the audio format you need.

If you are looking for a program that can accomplish all the tasks of removing DRM and converting music to compatible formats, DRM Media Converter is your best choice. Just with a few clicks, you can get non-DRM music quickly.
Video Demo: