My buddy has one of these David Clark ANC headsets and I wanted to try them out. My friend has not used them much as they don't really work in his ultralight like plane and I was thinking of buying them from him. Anyway I plugged them into my RV and took a flight with another buddy. He was using my regular David Clarks. The ANCs sounded good but very low. I had to up the volume on my intercom a lot and then my friends headset was too loud. Then when I tried to transmit I was getting a loud sqeel in my ears. My friend heard it also. I couldn't get it to stop when transmitting. It was like feedback from an open mike near a speaker. I played with the volumes on the radio and intercom. I had to switch headsets with my friend because I couldn't transmit. Anyone have any ideas what I was doing wrong? Someone said you shouldn't mix different types of headsets, especially the ANC ones. I think something could be wrong with them. I don't know?