First of all, hello and apologies if this is a recurrent question here. I have read the sticky honest. I've just added a subwoofer to my system and it does nothing but hum. Cant seem to get any audio out if it all. My receiver is a Denon 1513 and the woofer is yamaha YST-FSW050 and everythings connected as per this. With the sub lead disconnected theres no hum so I dont think the woofer is faulty, it just hums as soon as its connected to the denon. I've removed all the cables in the back of the denon and the hum remains, however when I unplug the HDMI out the hum then raises its pitch to a higher level. Everythings plugged into one strip but I've tried moving things onto their own sockets. I've tried a ground loop isolator and it didnt work, it made a small difference but the hum is still extremely noticeable and there is no audio output. Note, I'm clueless with the settings but the speakers are all set as Small and the subwoofer is set to on with LFE+Main in its settings at 120Hz. I've tried playing with these settings to no avail. Thanks!