Thank you both for your exaustive answers, my friends will appreciate your easy explanations But If you don't mind I would like to understand better two points: I tought that the mic for the noise-cancelling technology could catch ambient sound only if it listened outside the housing. I'm sure...

I have been arguing with some friends about the way my Urbanears Zinken could be used as a pair of microphones. After I have inserted my amplifier aux-in cable into one of the headphone holes (another input) and after I have powered the amp, I was able to hear on the speakers what I was saying...