If you are using condenser microphones make sure there are no electrostatic air cleaners anywhere near them. These look like static hits? Condenser microphones are also very sensitive to moist or humid air. They can cause similar electrostatic problems. This is why dynamic microphones are generally used under bad weather conditions outdoors. They don't suffer as bad from high humidity levels. I did not listen to the clicks because I don't need to listen to the clicks and I don't like your link site. But your screen capture rather says it all. Any kinds of electrical devices that have electrical motors and relays the switching such as for air conditioning and heating purposes can also cause these types of electrical clicks. This can and does happen with balanced connectivity equipment as well but it's less susceptible, since balanced cables don't quite act as much like long antennas as unbalanced cables. So I assume you are using the built-in microphones but the same thing happened when you didn't use the built in microphones and used an external preamp and the line input of the device? Are you also running on battery power or plug-in alternating current? Is it near a refrigerator?

There, that should get you troubleshooting.
Mx. Remy Ann David