Best Support For Rega 3

I have a Rega P3 with and Elys cartridge sitting on sorbethane feet on a piece of 1" birch on a built in entertainment center. Sounds good except a bit bright when I crank it up. Electronics are Linn Kinos and Linn Klimax amps. Have had advice from change cartridge to get a better platform to put it on. Was on thick marble, putting it on wood seemed to calm it down a bit. Any advice? Someone has suggested a base made by First Impression Music. Don't mind spending a few hundred bucks but if it's the cartridge I'd like to know. Thanks for your input.
They sound best on a short rigid stand, of light mass.
No sorbothane, rubber, air bladders, or that kind of stuff underneath.
Just a light rigid stand, like an Ikea Lack table or something like that for low $$.

That's a good start, and then you can decide if you like the cartridge, or not.

Try a Neuance shelf under the Rega.
A friend of mine loves his under his Rega.
i love mine under my Naim CDX2 and Nait 5i
Get a solid piece of clear Acrylic cut to size for you at a plastics place (at least 1/2 inch thick)and place the Rega on 3 Vibrapods(0,2,5 sizes)on top of this.You can super- glue 3 pointy brass cones(or metal)underneath the Acrylic slab for it's feet.The 5 Vibrapod goes at the back,the 2 in the next heavy spot at the left as you face the table etc.The Rega's feet sit directly on these.Somebody at Vinyl Asylum worked this out and then Stereophile recommended it for a Planar 25 and I have tried it on a Planar 2 with RB300 arm,works great.
I use 3 plastic rods under my Rega25 positioned so that with a slight push, the whole turntable is able to move slightly front to back. I have this on a plastic shelf supported by 3 cones. I use all of Expressimo Audio's upgrades and the resulting sound makes expensive VPI's run for cover. By the way - I have an extra Heavyweight and Non-felt mat (a gift after the fact) for sale. Let me know. Thanks