I have the Castle Compact 5.1 Home Cinema speakers connected to a Yamaha DSP-AX750SE amplifier, which works ok as long as the amplifier is turned on. My problem is that when I turn the amp onto standby the Castle Cube subwoofer starts emitting a very annoying, continuous humming after a short delay.
I've tried moving the sub away from any mains/speaker cabling to make sure it isn't picking up any interference but it still does the same thing. The humming does stop when I pull out the phono plug connecting the sub to the amp.
Any suggested solutions of how to leave the sub switched on and the amp switched on standby without getting the humming noise?