Hello,
This is very old post but I like to add into this post that the new version of firmware V5.5.0 or V5.5.3 for this camera just only support LINE-IN for any microphone set up, which meaning I believe requires of power adapter to power the microphone.
It seems Hikvision has cut off the MIC-IN in the later firmware version as based on earlier written post that V5.2.5 does work in yesteryear.