You might want to contact one of the plinth makers for the SP 10 as the SP 10 has to be bolted to their respective plinths (OMA,Albert Porter,Artisian Audio,Steve Dobbins).
Jonathan Weiss of OMA for sure knows because he ships all required hardware with his slate plinths. His email address is on the OMA website.
Jonathan Weiss of OMA for sure knows because he ships all required hardware with his slate plinths. His email address is on the OMA website.