You've not revealed what speakers. Instead of spikes I would look at the Isoacoustics Gaia II. They greatly improve performance and you can GENTLY with help move them. Once in place you might consider the carpet spikes for the Gaia footers as they greatly improve performance on carpet.
http://www.isoacoustics.com/products/gaia-series/gaia-ii/
http://www.isoacoustics.com/products/gaia-series/gaia-ii/