Granite stands for speakers experiment

there is a large Granite warehoue by me. I stopped by just to ask if they would sell me a small pieces. Turned out the owner is really cool and he let me pick some pieces from his "used" stock. He said he would only charge me a small fee for cuting ($25-$40).
So I picked 3inch slab and had them cut it to the size of the base of my ProAc D25 (10x11inch).

I placed my speakers on top of the 3inch granite blocks and of course the bass got better (ProAc woofer fires via bottom port), however the midrage got a bit bright.

I like how the low frequency improved but don't like what happened to the midrange.
Do you think if I was to use maybe 0.5inch blocks the midrange wouldn't be affected that way? I am guessing the cause is that the tweeters are now higher than they really should and it is not due to the material.

Anyone did that sort of experimentation? Maybe placing a little wooden blocks would be better?

PS: My room is carpeted.

Look into Herbies Fat Dots and/or feet. I used the Fat Dots under my monitors on a granite slab and got great results.

Good luck
Moving the speakers upward not only changes the interface of the woofer with the floor, ergo the frequency response, it changes how the high frequencies reach your ears and reflections off the walls and ceiling of your room.

You didn't mention why you thought granite would do something good, sonically at least, but using any other materials to lift your speakers say in blocks with 1/2 inch increments might solve your sonic conundrum when you hit the right height. Then you could go back to appropriate sized granite blocks or any other suitable materiel to get you the desired result. Personally I use hard(er)rubber to block the transmission of vibrations from or to my speakers and keep them as thin as possible so as not to deal with the issues you have encountered.
SYMPOSIUM Svelte shelf the same size as the granite on top.Granite is bright i once had granite amp stand then i got SYMPOSIUM Ultra Stealth amp stand everthing got much better.
I have used granite slabs and svelte shelves. Both were helpful, but I have to say with my speakers, I could'nt hear a difference between them and the granite is a lot cheaper.
I use granite pillars for our small surround speakers, wife would not have anything else in the living room; to modernistic, too techy,doesn't blend well with the decor. I have to admit, the granite pillars with small bookshelf speakers looks great and becomes part of the decor while serving a purpose. Not a granite plate, but an entire granite pillar. It works great.