hardwood floor and speaker

Either take out the spike, or use one of those cones. It's the same thing, in my opinion. You end up with the same surface area contact with the floor. Spikes don't isolate the speaker stand, they couple it to the floor, so that speaker vibrations run out into the room, or let room vibrations go up into the speaker stands, technically. I don't know if that makes it sound better or worse!

There's no such thing as a one-way out for vibrations, because if you remember, for every action, there's a reaction.

I like Stanwal's carpet suggestion

Yes, lots of options...I went with Herbie's under my floorspikes, sounds fine, and they're cheap.
Some people also go to the rounded- nut type of stand spike, sorry, forgot what they're called.
You shouldn't have any problem coming up with something.

Replace the spikes with a carrage bolt, then add some felt pads to the bolt head. That is what I did with my vandersteen stands on a hardwood floor.

An area rug can help with any unwanted reflections.

Paul

Follow this link to what could work for you:

http://herbiesaudiolab.home.att.net/spkrfeet.htm#cone

Yes, carriage bolts, that's it.
Also, if you like one of the Herbie solutions, there is one that allows you to slide your speakers if need be. I bought the wafers that go under my brass pucks and they stick like glue to the floor once the stands/speakers are on them, they do not budge...if you go that route make sure you know where you want your speakers.