Hi Lextek,
Using any type of rigid mount (such as a cone or spike, a slab of stone or wood, a rigid metal stand) will send unwanted vibration down into the floor from the speaker and the vibration will travel towards the stand which holds the electronics. It will travel up through the stand and into the electronics where it will contaminate the signal and impede the performance of the overall system. This situation is true for suspended wood floors and concrete floors.
The most effective method for supporting a speaker will be with a high mass, high absorption platform that has the ability to absorb the unwanted vibration before it can enter the floor and contaminate the rest of the system's components. The specific methods and construction of this platform is critical for best performance.
Please let me know if you'd like me to elaborate further as well as provide measurements which show the effectiveness of this type of speaker support.
Best Regards,
Barry Kohan
Disclaimer: I am a manufacturer of vibtration control products.