I started my local public radio station, as I do every afternoon, and my Sonos played a Sonos advertisement for 30 seconds instead. That is an unacceptable behavior, so I threw the Sonos out of the kitchen window. It is now lying in the garden, and it will not be invited back in. My question (I searched and as far as I can tell it has gone unanswered on this forum) is what is the minimum safe depth at which I will never see it again?