Lifting speakers off the floor, subs or floorstanders, will alter the frequency response as heard at the listening position. I think of this whenever I read a post where in someone praises the practice of placing things under speakers for isolation, etc, and wonder how much of the change is due merely to the elevation, albeit small yet extant. FWIW.
Rel Does Not Recomment Isolation Stands
This came as a surprise. I had just assumed that it should be isolated. Then I discover I was wrong. after doing some research for isolation for mine. Even though I am NOT electronics engineer I think this is an interesting subjet idea. Pardon my utter ignorance. I should have known there was an opposing view. Always is. Just didn't think of it