Putting floorstanding speakers on stands...

If you raise the speakers off the ground then you may get better or worse bass (usually less). Another approach is to tilt the speaker back, so that it fires at your ears, but the distance between the LF driver and the floor is maintained, which will help keep the bass reinforcement the same.

I agree with the above posts, although I have had my success with Sound Anchor stands, first their standard stand for B&W Matrix 803's, then custom cradle stands I had made for my Alon V's. The stands raise the speakers a bit, offer adjustability in the tilt of the speaker by adjusting the spikes, and add mass loading when the heavy stands are coupled to the bottom of the speaker. IMHO the bass is much cleaner and better overall. I may have to try spiking the stands into some hockey pucks thanks to woodman!!

I use Sound Anchors on my floorstanders.

I had to raise my floorstanders when they were set up in my old place in a smaller room, where I had to sit closer than was ideal with the model in question. I don't do this anymore in my new place, but it can be helpful under certain circumstances, so don't hesitate to at least experiment using some kind of makeshift 'stands' for them. I used short stepstools myself, but whatever you use (bricks, blocks, phonebooks, boxes filled with newspapers or magazines, all with a piece of plywood or something layed over top for stability), check your results before laying out the bucks for something real. BTW, you could also look into lowering your listening chair situation in some cases.

I have not used stands but have experimented with tilting the speakers back by adjusting the height of the spikes (as described in the Merlin owner's manual). Well worth the time to find a position that suites your taste regarding imaging.