I have a pair of Wilson Audio Alexia and I had them on the casters for quite a while, ever since the Dealer dropped them off and set them up, and the left them on the casters. Later on I conjured up the courage to put them on the Wilson's spikes that the speakers came with. In so doing I noticed that the bass was missing and at that point I went and got two JL Fathom subwoofers to enhance the bass. They did such a fine job that I got complaints, These subs are quite powerful. What I did next is to eliminate the subs and got Isoacoustics Gia Titan speaker isolators for the Wilson Alexia. I had some issues with the screws and lugs at first because I got the wrong ones. I waited a few weeks before I got everything in order. And I must tell you that it was worth the wait. I waited almost 4 weeks before I made any public comments about the results I was getting from my listening sessions after I installed the Gias. It was unbelievable, I didn't expect such a difference. The bass was punching, soundstage was wide and focused; everything sounded just like I wanted it to sound from the beginning. I waited 4 weeks, just listening to the system every day to see if anything would change. In the past I got expensive interconnects and the system sounded great but after a few days it wore off and I could not recover the initial experience. So after installing the Gia Titans, I waited just to make sure that what I was hearing is really what I heard from the the start.
So my advise it to take your speakers off the spikes and get some speaker isolation feet instead. At least try it, because everyone's setup, hearing, etc. is different.