A dedicated stand for the turntable is required. In the case of the SME, a light weight rigid stand that is not very tall, is recommended. Put no other gear on the turntable stand.
As for the other gear, the Sistrum racks are said to actually improve the soundstage and imaging, when placed between the speakers. My preference is always low racks, as tall ones are less stable, and more intrusive. Sistrum has a trial period for auditioning, so you could try them at no risk, if you like.
I am not the highest authority on equipment racks, but I do know how a turntable should be sited, and my advice above will yield better sound from your TT. Light, low, and rigid.
As for the other gear, the Sistrum racks are said to actually improve the soundstage and imaging, when placed between the speakers. My preference is always low racks, as tall ones are less stable, and more intrusive. Sistrum has a trial period for auditioning, so you could try them at no risk, if you like.
I am not the highest authority on equipment racks, but I do know how a turntable should be sited, and my advice above will yield better sound from your TT. Light, low, and rigid.