Is There a Way to Lessen Vibration On Cables From Powered Speakers

I can tell you what that will sound like but it is a cheap experiment and that way you learn from experience. The more effective answer is route the cables in such a way that the vibration is crosswise rather than axial. In other words put a bend in them near the speaker. This will help prevent the majority of vibration from traveling as far.  

Put the speakers themselves on Townshend Podiums. This will reduce ringing in the speaker, which will reduce ringing in the wires. Use cable elevators with rubber bands or other similar means of isolating the cables.  

In spite of appearances the best approach is to allow them to move, but in a way that allows them to dissipate energy without transmitting it to other stuff, which always results in ringing to some degree or other. 

@millercarbon

I would be scared to bend the wire.  It's silver and I am not wholly certain how they crimped or soldered the connectors.

Would foam pads inserted between the connectors absorb some of the vibration? I did a small experiment with a foam pad I had laying around.  I cut a few squares and placed them between the connectors.  Now those foam pads vibrate along with the connectors.  So, I can't really tell if I offloaded any vibration or made it worse. :)

If it doesn't bend how does it get there in the first place?

get the plate amp out of the speaker as a first order priority..

@gaukus

Have you considered dismantling the Audioengine speaker and damping/isolating the different components/drivers?

You are attempting to minimize the cable vibration, which is actually the manifestation of the vibrating speaker. Its the speaker you should be addressing and then maybe the cables wouldn't vibrate? The computer speakers you are working with will have natural limitations regarding cabinet integrity, etc. 

Am I the only one sensing a bit of dejavu....somewhat of a Kenjit 2.0 vibe?