Sorry for asking the question for the millionth time...

I believe I have my audio system as dialed in as its going to get. I have a great mix of gear, cables, and I haven't changed my speaker positions ior room treatments in months because I'm fraid I'm going to ruin some part of the sound. That said, I've come to realize that my speakers aren't set on the floor properly. I'd like to try some things.
Here is a pic of the speaker as it sits now:

The speakers are Salk Sound HT3's. They weigh about 90lbs, and have a 10" bass driver. They currently sit on a suspended wood floor with a layer of MDF on top of the normal subfloor. I have carpet pad and berber carpeting, and I'm using the supplied cones (they are wide and rounded on the bottom) under the plinths. In this configuration, the speakers can rock in my direction with little effort. Its as if they are sitting on springs, which I suppose they really are in a way. I should also note there are only 3 cones screwed to each plinth by design; 2 in the front, and 1 centered in the back.
I researched getting narrow spikes to punch through the carpet and pad to the subfloor, but I read that's likely not best for my situation. I read isolation might be best, so I've been looking for a cost effective solution. I have come up with a couple thoughts:
1. Get some sort of granite slab to lie on top of the carpet, then set the speakers with cones on that.
2. Get the granite slabs to lie on the carpet, put some sort of Herbies Fat Dots between the granite and plinths without the cones.
3. Leave the plinths with the current cones on the carpet, and put the Fat Dots between the plinths and the speaker cabinets (sticky version obviously).
4. Remove the cones from the plinths and just use Giant Sliders between the carpet and the plinths.
5. ?
I have very nice clarity and imaging, but it could always be better. I'm looking to tighten up the low bass a bit if possible
Thoughts?