Loud buzzing noise

I would check the caps on the power supply. They are rather large electrolytic capacitors that will look like they burst and/or leaking. When these die, the caps ground and the sub will make a loud buzzing sound. If you are handy with a soldering iron you can replace them yourself. Replace them with the same voltage or a little bigger and same with the size.

If the cap. says 16v 4700pF on it, for example, a 20v 5300pF or a 16v 6200mF cap. will work for this application.

If you pull out the "input" cables and the noise stops, you have a problem with the "ground" and you have to check if there isn't a loose contact inside the plugs. If it doesn't stop, your amplifier is the problem and that mostly is a bad contact on the board in the pre-amplifier area.

Buzzing is usally AC line noise leaking into an un-shielded cable somewhere or a floating ground. If the AC plug is reversable, try that. make sure all audio cables are pluh\gged in tightly at each end and routed away from or at right angles to any power cords and away from other sources of strong magnetic fields like TV's. I've also seen variable track lights induce noise but it's usually minor.

If it still does it with no cables attached it's an internal amp problem.

If you get your system up and running and hear an audible buzz or hum, the first culprit to look at is either the powered subwoofer or your reciever feed at the entry point to your system.

yes. A good idea. Kill power to the sub, then unplug and remove everything from the sub. go ahead and plug it in again and check for buzzzz.
That is test one. if you have buzz still, its the sub assembly. bad luck, but not impossible. If the buzz is gone its one of the signals to the sub. They can produce a buzzz without any signal coming from your stereo equipment. Replace the feed line, enjoy! BTW...Kef sure does sound clean. good choice.

check the male plug

Buzzing noise - contactor. maybe a bug got in the contacts or maybe the coil is bad but in any case if you replace the contactor the buzz will go away.

the loud buzzing noise isnt the xbox its the powerbox the one tht you plug the power cord into b4 u plug it into the back of the xbox when the buzzing happened to me i just shook it and it went away

Try playing with the connection, sounds to me maybe the jack is going bad or has a shorted connection. Plug it in and out slowly to see if that's the issue.

switch your subwoofer off from the socket for at least 30 minutes and check if the noise is still there,if its still there open it and play a movie then press it lower if the sound stops then you will have to put some toilet papers at the back of it ,thats what I did to mine.