Check all your connections to make sure they do not have a stray wire to ground. Both the amp and the AVP should share the same common ground (as should the rest of the equipment). If the ground plane is different between the various pieces of equipment it allows current to flow across the ground and usually is the cause of the hum. I don't see a surge protector/voltage regulator in your profile. I don't subscribe to the need for voltage regulation but for lightning protection and to provide a common ground they are great. Inspect the ground connectors on the AVP and the amp assuming the AVP has a grounded plug. If it doesn't have a grounded plug, you may need one. Sometimes the ground in the receptacle isn't secure to both outlets. Try plugging an extension cord into one receptacle and powering both pieces of equipment from the extension cord. If the hum goes away the house circuit is suspect. Don't run this way but it is a good way to check the receptacle.

Disconnect all the inputs to the amp and turn it on. If the amp is the problem you should hear the hum. If no hum, then plug in one input at a time until you do hear the hum then check that cable by swapping it with another. If both have the hum then check the connector on the AVP and the Amp.