spikes for speakers or something else?

Coupling speakers is good, especially if you have solid floor, but isolation is even better in my experience. There are options for most budgets.

If you're lucky the spikes will drain resonant energy from those monster cabs. Get longer ones that'll pierce the carpet and pad thru to the sub floor.

How about larger spikes? With few exceptions, I find that spikes offer the best coupling. One of the most important issues in speaker placement is removing the ability of the cabinet from moving around in reaction to its own energy generated from the drivers. Take a look at this previous thread that might glean some information. My system has 176 lb.(each) speakers on a rather narrow footprints. Small spikes were good, large spikes are sounding better. Happy Listening!

http://forum.audiogon.com/cgi-bin/fr.pl?cspkr&1131824235&openflup&2&4#2

I would get a big heavy piece of marble or wood that covers the whole speaker base and spike it to that. That is usally the best solution. Spikes in carpet will do very little. Islotion solutions are not bad eithor but you have to find the one that works.

You might try Herbie's Audio Lab Big Fat Black Dots between your speakers and the marble. They have a 90 day satisfaction guaranty. These are truly great between my speakers and hardwood flooring. The cost is about $50 for a set of six.

Have you tryed putting the spikes back on with the marble underneath,i use spikes with paving stones on top of the carpet,this works best for me .Ray