Is this issue with all of your sources or just one? If only on one source, then isolate the issue to it. If it occurs on all of the inputs make sure your interconnects and speakers wires are separated from your power cables by at least a few inches. If that doesn't fix the issue then:

Swap a few of your cables between speakers and see if the static follows the cables you changed. If it does the speakers are fine,and the problem lies upstream. If it remains on those two speakers then check their connections to make sure they are clean and tight.

If the problem is upstream, put all back to normal and then swap the interconnects to the amp. If the problem follows the swap, the issue is still upstream. If it doesn't the amp is the issue. Check to make sure all of its connections are clean, tight and clear of any stray wiring. If the problem remains on those two channels, then the AVM-20 is the source. Check all of its outputs to make sure they are clean, tight and clear of any stray wires.