Animation Nodes change texture value with proximity of empty object

Hi and a call for help for using Animation Nodes. And this is my first post in the community. I have created a grid loop of spheres placed in random places and scaled randomly. The spheres have an Emission texture applied. I have an empty object that is my Effector. The aim is to have the Emission strength increase in value as the Empty object passes over the spheres. It will travel from left to right in the camera view. Ideally, I need the copied instances also in the z-direction to have the increased strength. Currently, I have the Empty object calculating its position against its source and using that value to effect the Cycles Material Output strength. Problem is that the value affects all the spheres and the value strength is weakest when it is near the object. Also, I need it to calculate the value of each sphere proximity. Thxs