Steer Emission Strength of an Shader by the position of an unrelated bone...how? There is a armature.bone, which position is driven by a noise modifier on its
f-curve (y.position).

I want to make a LED-material flicker in its intensity in dependence to the
position of that bone.

The bone has no logical relationship with the LED-object. 
The LED-object is not moving.

How can I achieve this efficiently?
You can set a driver to a value node
Right click on your value node and choose add driver
then just choose transform channel if not as default and select your object/axis  



in the expression field you can do some operations to change/map you values
if you want it 1:1 then just put in the variable name, in this case "var"