This helmet was recommended to me by a friend who is an engineer sound and I confess I separates me. This helmet is one of the best for me. After trying brands like AKG and many others, I remain faithful to this helmet. Perfect sound you need to know to appreciate because it renders flawlessly. On an iPhone, the sound will not be too high because I think that the iPhone lacks juice to power it. On an amp that's pure happiness. Since it is a bit big for my little head, I do not walk in the street with but I take when I take the train. It fits perfectly to the ears and shakes it takes to not having earache and not lose it. I have one at work and one at home. At work I am in open space, I sometimes met without music just to be in my bubble because it insulates very well (30dB). At home I listen to her and I play with no worries. For the price and the sound quality, no complaints.