Mass is your friend when trying to tame vibrations. It will increase the energy needed to excite and lower the resonate frequency. Coupling masses can only improve the situation. Tonearms and exposed tubes are bad, after all they're light and cantilevers (like a springboard). High sound pressure levels and soft floors (wooden) are obviously bad. Your rack should have spikes that penetrate the rug. Most footers try to isolate the component from the rack/floor. If you have a concrete floor that's counter-productive. Isolation footers should be designed for a given component weight (the vast majority are far too stiff to give the needed compliance). The other challenge with isolation footers is matching them to each sub-component (transformer, inductor, capacitor, plinth, platter, tonearm, etc.) inside the piece.
Your concrete floor is a blessing, take advantage of it and try coupling everything to it.