"Michael McKelvy" wrote

Good speaker points firmly attached to the speaker
bottom and completely coupled to the underfloor will
reduce audible cabinet residence

I'm going to assume you mean resonance. Audible
cabinet resonance is a sign that your speakers are
very cheaply made. Spikes won't help this problem
AFAIK.

Do you have any empirical experiences with spikes?

Oct, 2000 , TAS - What's Wrong With Speakers
by R.E. Greene

"But as soon as a speaker gets an input signal, it
starts doing things it shouldn't and starts making
noise, not just the music it should be making. Cones
and surrounds flexing, mechanical structures
vibrating, cabinets flexing in unpredicted and
unpredictable ways, air flowing turbulently,
electrostatic diaphragms vibrating chaotically
on the scale of small areas even if they are moving
regularly on a large scale, such sources of noise
are everywhere.

How much noise are we talking about here?
A lot, a whole lot by the standards of noise
levels in electronics and recording systems.
Speaker noise appears only 20 to 30 dB down
from signal in some cases, and even the
cleanest speakers I know do not get the noise
down much more than 55 dB or so."