The fact that the voltage selector switch on the "belly" is only with the supplied key (or screwdriver) can be switched, is in my opinion an excellent protection against erroneous operation represents (which indeed could result in the destruction of the connected device easily) ,
There is an extensive range of plugs supplied (incl. USB) whose polarity can invert by reverse plugging (USB adapter can, however, usefully only be inserted in the "right" orientation).
A buzzing, as noted by other customers, I can not see - but this could be due to my pig ears ;-)
For life I can not say anything yet, but will in case of problems, of course, add a response. From today's perspective, I can thoroughly recommend the product anyway.
