I bought a Logitech C920 webcam for my late 2014 Mac Mini. When I make FaceTime calls to friends, they tell me that they get a lot of echo of their own voice. I use external speakers and after some testing, find it likely that their voice is coming out of these speakers and going back into the built-in microphone of the C920. I bought the Logitech on the recommendation of what I had read on various reviews and forums, including here. Clearly there are others who use the C920 and other webcams successfully with FaceTime. Advice, anyone?