Hi All I have a problem with my subwoofer that is humming. I have a Pioneer S-W80 sub that always emits a very noticeable hum when its powered on. Its new and I only set it up over the weekend. I have searched your forum over the last couple of days and have read up on earth loops and the correct connections and amp set up but the question I have is quite simple. I have connected the sub via line input to a Marantz SR5200 receiver. As soon as the sub is powered on it starts humming, its quite loud and is still noticeable over dialogue and music etc. I have checked the earths (sub earth connection on the plug is not connected) and the connection to the amp. After reading previous posts on this I have also ensured that the cabling for the input is not near the power lead for the sub. I have also repositioned the sub and used different cables. I isolated the sub in a different room, not connected to anything but as soon as its powered it starts the hum. the level and volume controls on the sub do not make any difference to the volume or pitch of the hum itself. I'm starting to think that this is faulty as i do not have any other point of reference. Is it normal for a powered sub to hum in this way. I suppose I expected some very low level noise but not something that is so distracting.