I wouldn't go spikeless with speakers on any surface. Unless both your speaker and your floor are absolutely flat, they'll rock a little, and that ain't good. On carpet, forget it, they'll be wobblin' and dancin'. Stabilize those bad boys. Decouples the bigguns from the floor, which can be very helpful as well.

I've used Mapleshade's big brass cones under both Steve Culton's Straight 8's and my Pi Audiophile 3's to excellent effect. Doing it in threes is easiest. As long as you have a square back, you can cheat with as few as one under the front.

Oh yeah, putting your Paramours on maple slabs sited on a trio of brass cones each is very nice, too. Not subtle!