What should I use between spikes and wood floor?

I put a slab of marble beneath the spiked stand with felt pads beneath the marble to keep it from scratching the floor.
works pretty good, you can pick up the marble from home depot for 3-4 bucks a tile.

Instead of spikes I use common hex bolts with same thread as supplied spikes. They don't mark the hardwood and provide solid contact. Just be sure to thread a nut on the bolt for tightening.
I may be cheap but spending alot of $ on some esoteric feet strikes me as absurd when the local hardware store sells nuts and bolts for pennies.

go to audiopoints.com. That is Star Sound Technologies's website. They have a brass coupling disc. Will do just want you want it to. Looks great, as well. peace, warren

I second the audiopoints...got some for my dad...they are soooo damn flat that they are actually pretty hard to pick up.

I went a more custom route myself but didn't save any $...and I'm sure they aren't as good.

I use pennies with a little felt on the side making contact with wood floor. It works fine.