My experiments with the Basis Mk5 with Graham Ceramic +Tungsten arm, (when I owned it), was that any device (re:) Black Diamond Racing shelf, Purist Audio Platform, four inch Granite, solid Maple butcher block shelf, etc. all were detrimental to the sound.
The Plexiglas making up the lower platform of the Basis seemed to reflect or react with the device directly beneath it, regardless of size or materials it was constructed from.
Best results were finally had by using the stock Basis feet sitting on a four inch diameter, four post stand with open architecture. Constructed from aluminum and filled with silica.
Best results are obtained when the stand and turntable are kept fairly close to the floor. The taller the stand, the less effective, especially on pier and beam foundations.