How thick should the front baffle of speakers be?

The woofer should move, but no other part of the speaker! :) I think that it matters to some degree. A woofer exerts tremendous force on the cabinet. Any flexing in the front baffle could lead to Doppler-like effects as well as additional, unintended sound sources. The ideal speaker's output is ONLY from the drivers. This is different than a musical instrument where the strings or membrane AND the body resonate together.

MDF is cheap though. :)

Best,

E

So I shouldn't be able to put my martini shaker on top of the speaker and wait 10 minutes to sip?   :  ) 

+1 Erik
That makes good sense since eliminating micro vibrations to the cabinet through footers etc. greatly increases speaker presentation. I never knew what mine were capable of until I put them on ceramic ball type feet. 

While I think solid construction is important, another sometimes overlooked thing is keeping the speaker from moving in 3 dimensions. A woofer can make the whole speaker rock back and forth. YMMV of course depending on the mass of the speaker, but a cheap tweak is often simply to add mass to the top of a speaker.

Tall skinny speakers benefit the most. It's pretty amazing.

Best,

E