The Z2 is very silent, and I used it during my travels, mostly with success.
the only issue: I could not set it up to *not* turn off automatically (after it decided to turn off on its own one night).
support did not give me good instructions on how to set "no automatic turn off" although I emailed a few times and response was very prompt. I was out of the country and could not call, so I settled for it as is.
Rating: