a hum conundrum
i have a arcam alpha 9/9p set up in which the power amp is prone quite audible hum.
the amps are plugged into a good quality mains block and the mains block is plugged into a double wall socket ,
with a small table lamp in the adjoining socket.
when i switch on the lamp ,the hum disappears for a few seconds before coming back and the same thing happens when the lamp is switched off.
can anyone tell me why this happens ,if it tells me anything about the cause of the hum and if it points towards any cure?