The spikes should help, I don't see how in your situation they could not.

Easy solution:

If you are single, spike the speakers directly to the floor and don't worry about it.

If you have spousal responsibilities, spike the speakers directly to the floor and ask forgiveness if your spouse notices and gets upset.

Are we not audiophile men?

I have a similar problem because (1) my speaker stands have to use spikes or felt pads, because the screws on the bottom aren't flush (so it'd be wobbly) and (2) I rent, so damaging the floor is a no-no.

I stick felt pads or pennies underneath the spikes (I couldn't tell the difference in sound or bass response). They eventually poke through the felt pads, though. If you discover a better solution, let me know. It'd be nice to have something durable that doesn't scratch the floor.

Mail order audio sites like Audio Advisor and Mapleshade sell footers (like the ones below) that go under the spikes. I've got 2 1/2 inch spikes piercing carpet to the slab- hope the wife doesn't figure it out.

http://www.audioadvisor.com/products.asp?dept=66&pagenumber=2&sort_on=title&sort_by=