bolting speakers to floor?

Check out the speaker/amp stands by Sistrum. They would provide precisely what Blueswan is suggesting. Robert at audiopoints.com is very helpful and could offer additional suggestions, I'm sure. It's even a toll-free number if I'm not mistaken. Good luck.

Since I have a baby issues I constructed a 1Mx1M MDF platform with spikes at the corners that is being flexibly bolted onto the platform so that I could actually rotate the speaker(since it's originally stands on the ball bearings) and it turned out to be the great tweak. In addition the speakers are loaded with 50lB of a lead shots

If they keep getting moved, yes, I would bolt them to the floor.

Blueswan and Jctubes are correct. Bolting your speakers to the floor may keep them from hitting you in the head during an earthquake but will screw up the sound the other 99.95 of the time. Sistrum platforms will transfer at a high speed, all extranous noise to ground. If properly sized your speakers will remain stable resting upon Sistrum Platforms and will at the same time become more musical.

My friend offers an engineered composite stand solution using (removable) adhesives. This assembly could be either spiked or bolted to the subfloor. If you use this solution you would not have to penetrate your speaker cabinet. An added benefit is that it increases the rigidity of the speaker. Contact me via email if interested.