I've got a Linn AV system and I'm getting a lot of hum from the speakers. After a bit of investigation I've narrowed it down to the SKY coax feeds and the TV aerial coax feed. If I disconnect these the hum goes away. Given that ground loops occur when equipment is connected to different mains supplies, how do I fix this as both Sky and the TV aerial is supplied via a distribution system which is powered by the 'landlords' supply. Is there an earth fault in the distribution system?