You do want rigid metal stands; that is correct.

The Sanus Steel Foundations are very good, and the price is reasonable. Many manufacturers sell dedicated stands, but they tend to be very expensive.

Another thing; always get stands that have a hollow metal tube or tubes in the center, so it can be filled with lead or steel bird shot for mass and damping. It is important to do that.

A material that is good for placing under the speakers is the material that is sold at RV stores to keep things from sliding around in cabinets. It comes in a roll that is maybe 10 feet long and 10 inches wide, and is sort of a thin tacky waffle-rubber material that can be cut to size with scissors.

The equipment you have chosen is very good for a modestly-priced system. I am sure you will enjoy it.