Speaker Spikes and related items....

Hi all!  My Paradigm speakers (monitor 5"s and Monitor 9"s) have interchangeable spikes to use when you are putting them on carpeted floors.  Now I am going to put them in our new addition with hardwood floors.  I see many different options and products that have their own systems with spikes and bases to put the speakers on to slightly raise the speakers up and isolate them from vibrations!  All well and good, but are the thread size for the screw in spikes a universal size or do the thread sizes differ by the brand of the speaker.  Thanks for the help.  FYI - the reason for my interest for these things is I have to position one of my speakers over an HVAC register and I do not want to totally impede the airflow from the register!!  Thanks, Kevin