Amazing system (I particularly like the Porche on top of the HD621!)

Have you tried the speakers (and equipment) without the marble plinths? You might get a different sound so it's worth a try. You may or may not like the difference. If you do, you could try something like oak cones direct on the wooden floor and racks, and see if you hear a nice difference (Russ Andrews sell good ones if you want to try).

Enjoy (I'm sure you are)!

HC: 861v4/ID40/LPS, DSP5000, DSP5000VC, DSP3100, SW1600, HD621, Oppo BDP-105, Sony VPL-HW55ES
2-Channel: Oppo BDP-105, TEAC VRDS-7/Trichord Clock 3/PSU, 551, Quad 303, Harbeth Compact 7ES-3, Kimber cables, Russ Andrews mains and supports.
Previous Meridian: 5000C, 5200SL, 7200.2, 6000, 562V.2, 568.2mm, 800v4, 808.2i, 818v2/v3, 861v8, 502