they are solid state pieces of metal and wire and resistors and stuff, you could shake it all you want, put it upside down and spinning if you want. Wont matter.
Distance to speakers shouldnt matter either but since it comes from the amp to the speakers I have mine (for the front) up under the passengers feet behind the glovebox. And for the back speakers, I put them under the back seat.
Place them wherever you can hide them, you shouldnt need to see them unless you want to show them off.