Question: The iPhones all were using the audio output jack. I surmise that they were plugged into a portable battery powered amplifier, otherwise the sound would not have been audible ten feet away on a subway train, which it clearly was. Did you see that, or was it mentioned and I missed it?
These guys will be internet heroes in another day or two. Awesome marketing. I'm not much for most of the so-called "modern rock" genre, but this was worth the listen.
Yeah... there was clearly a white cable coming from the audio out jack on each of the iPhones in the video... and in one shot there was a glimpse of what looked like a small audio amplifier on the floor... I suspect they had some kind of mixer involved too.