Should I use Speaker Spike / Isolation Base or Something?

Another vote for the IsoAcoustic Gaias. Marten loudspeakers have teamed up with IsoAcoustics for their higher end models.

@stereo5
Your speaker will still be wiggling around and muddying the transmission of your sound.
Blowing in the wind.

@miglik   Your speakers too will be blowing in the wind if you don't couple them to something solid.

The issue is to prevent the speakers oscillating relative to your ears in the listening seat.  That oscillation will oscillate the sound you hear.
Simple physics.

Try not to listen too much to MC.

Noted MC isn't coming in on this.
Boing boing!

Clearthinker is absolutely right. Any vibration of the speaker is distortion. The game is to hold the speaker as rigidly as possible under the circumstances. Springs are beyond belief silly even on a wooden floor which is going to vibrate at it's resonance frequency regardless. A concrete floor is wonderful as least for speakers. Not so much for turntables as there is rumble that will travel through a concrete floor. Speakers should always be spiked if possible. If a stand is used they should be firmly attached to the stand and the stand spiked to the floor. 

clearthinker, you are wrong, wrong, wrong.   Best sound I ever had and I have been doing this over 50 years.   Try some of the GAIA footers and you will eat every one of your words.  Do you like the taste of crow?    And, I will leave it at that.