When I received my Poseidon, I connected to the central post, an Eartha Apollo Infinity RJ45 that in turn connected to the AQvox Switch. The result was very satisfactory and certainly superior to the connection to a Silver Minimus.
Well to further improve the ground connection of the switch, I bought an Eartha Apollo Infinity with Schuko connector and connected it to the same central pole of the Poseidon and the Shuko to a free receptacle (HC) in my Shunyata Denali. The result was not good.
PO not recommends to share the post with another grounding when using it for power outlet grounding with spade/Shuko cable. There is so much noise and dirt in the power that this grounding should be done by a single post or seperated Silver Tellus doing only this.