You can set the gain in H (igh) or L (ow) as the output voltage, which allows to adapt to his helmet Characteristics
I would have liked a slightly longer battery life, but its still quite correct (about 4-5 hours).
The cord comes with good looks in any case its works fine with the line out of my IPOD nano v3
The only downside may be that the price could be less seen it "only" headphone amp.
and the E7 for the same price has a DAC, but I do not know if it offers the same service side headphone amp.