The GRIP is NOT the only thing that is matter. You have to play with the plating, the body molding material and the conducting material as well. I am a fan of PS Audio myself, but to shell out that much money for their Power Port or now the Power Port Premier, I would go for the Oyaide's R1 or SWO-XXX. A little bit more expansive, but more obvious improvement.
Have fun.
Have fun.