I finally just got my new 3.33 6 core mac pro with a 27" ACD and have been doing some preliminary testing to make sure everything is behaving and working as expected. Up till I had this machine I've been using Tiger 10.4.11 so jumping "up" (?) to Snow Leopard 10.6.4 takes a little getting used to. One of my tests involves the Sound Preferences, specifically Input. I am not sure the microphone is working on the ACD. If I set the sound input to "Display Audio" - type USB (also tried all the others too) then I would expect to see some activity on the Input level display. I don't see anything no matter what the Input volume setting is. I can bang on the ACD near the microphone, clap my hands, shout, whatever and see no input level activity. On the other hand I also currently have the Sound preferences up on my nearby Tiger machine and it's microphone can hear me typing this as indicated by the Input lever meter on that machine. So I am wondering if the microphone working on my new 27" ACD or some additional "magic" needs to be performed in Snow Leopard that I am not aware of. In case anyone should ask, yes, I do have both the mDP and USB cables plugged in. And I got the Input volume turned all the way up and still nothing. Can anybody help?