I want to make phone calls using my mac mini. I purchased a headset in which the speakers work but the mic doesn't seem to. When I went to the mini user manual it said something about not providing power to the audio input jack. Does this mean that I must use an active (i.e. powered) microphone, or will a passive one work? Am I overlooking something else? I would appreciate any help from someone who knows more than I do on this, which isn't much. Thank you.