How Good Is A Marble Slab at Deadening Vibration

Great I think, the heavier the better. I used Marble under my tube amps when I had them as I felt they looked better in the room. I now use granite slabs under all of my equipment. All the source equipment is in a closet but the amps now.
If you do not use some kind of rubber or a mix of cork and rubber most any stone item will ring.
You can buy rubber and cork squares from Mapleshade for way too much money IMO, or you can purchase them on Amazon. They are larger but you can cut them down. They are rated for 50 lbs. per square inch so take all the weight in account. You can use any extras for under equipment.
BTW I sold the Marble with the amps.

To Hevacl, does the sale of rubber and cork squares appear in the audio accessories section on Amazon, and who makes them, or is it DIY?? I do not want to elevate the slab more than one half inch off of the surface of the wooden table. Thanks, Jim

To those who responded: Though final conclusions have not been reached, Operation Marble Slab has been generally successful producing benefits in midrange clarity, some increase in bass, and overall, a more coherent presentation of the music. However, nothing was startlingly different.

The following music was used: "E Power Biggs Plays Bach" David Bowie's "Ziggy Stardust"; Steely Dan "Can't buy a Thrill" and one Belle and Sebastian's track titled Lazy Line Painter Jane...hard to believe a calliope would be converted into a powerful rock instrument; Lastly, Mott the Hoople's LP titled "Mott" particularly the last two tracks side 2: "I am a Cadillac" and I Wish I was Your Mother"

One anomaly: On some music there seemed to be less slam and dynamics, mostly on LP's I have heard deeper pedal notes on the Bach LP which was gifted to me 37 years ago. On the Mott the Hoople LP, there are two mandolins that drive the tune. "I wish I was your Mother"; they had less sparkle at the top of their range from what I can recall from before. The CD playback seems to have reaped the most sonic benefits from the marble slab.

Finally, though I cannot quantify it, I felt that I could hear or at least identify the weaknesses of CERTAIN COMPONENTS, AND CABLES. Mainly, the Red Dragon monoblocks amps which overall are very neutral, but have below average lower bass and resolution. In addition, the Morrow MA-3 IC which connects a Musical Surrounding Phenomena II phono stage to the Rega P3-24 crowned with a Dynavector 10X5 spike. MA-3 just did not cut it Transient response on some LP's sounded slow. OK,I know this is a subjective impression; it is probably because I have NEVER liked it to begin AND WAS NON-RETURNABLE BECAUSE OF BEING USED.

The other weak link is the Audio Art SC-5 standard speaker cable which is good, but not the best wire for the AZ Adagios wide frequency response....that is why I keep looking for and asking about better speaker cables in various threads.... SO THAT IS IT FOR NOW!! I will try the cork and/or rubber matting as recommended by BW, and Hevacl. Thanks again to all. Jim

To Nonoise, Many thanks, this stuff is alot cheaper than Mapleshades' cork and rubber Isoblocks. Will give them a call. Jim