The BeachTek DXA-5DA (pictured top) is a passive adapter, which doesn't have phantom power – you would use it with self-powered condenser microphones or wireless receivers, or as an interface to an audio mixer.
It has two inputs, a level meter, and a "unique AGC Disable feature controls the wild swings of the Auto Gain Control that plague most cameras," which reduces noise during quiet moments of recording so that you can record cleaner audio. It fits under the camera and can also be mounted to a tripod. It is powered by one 9-volt battery and costs about £290.
By David Fox