Sony Bravia - annoying hum
 

I noticed the other evening when i had this on a low volume that there
was an annoying hum coming from the speaker. If i mute the tv
completely it goes away, but as soon as the speaker is switched on the
hum is there. it was on all channels so I presume this is a
fault/feature of the set? Or perhaps its the new sky + box. I'll have
to try it with a DVD, but I'm pretty sure its the TV. Anyone else got
one? (KDLS32A12)