Effects of protection disks under spikes

First, yes you are thinking about this stuff too much and second why don't you try them out and give them a listen?

Metaphysics, no you are not... spike marks are a genuine concern for many audiophiles. I use the Walker Discs between component cones and the shelves, and also between equipment stand/speaker spikes and the floor. They provide a very good coupling because transmitted vibrations are apparently trapped in the dense lead by the brass ring. You may get minor surface scratches if you slide them around fully loaded, so have your locations picked out ahead of time.
Good Luck