Out on the tiles...with speaker spikes.

I've just recently moved into my new house, which is entire tiled. I want to continue using the spikes my speaker and stands have, but don't want to scratch the tile.

I know several companies make little 'feet' to go under the spikes. Does anyone have any experience with these? Which ones seem to be the best as far a keeping the speaker stable, not raising them too much and obviously not damaging the tile??

Thanks for any help you can give me!