Thank you for your kind words about your positive experiences with the KH 120.
We can confirm that there is a VERY small hum from the electronics that is audible from the back of the cabinet at VERY small distances. At any realistic listening distance (i.e. >50 cm) it is not audible, so in all practical applications it is not a problem.
Best regards, Andrew Goldberg Product Manager - Studio Monitor Systems Georg Neumann, Berlin.