I have not built my sub yet, but according to WinISD I will definately need a SSF. This is the primary need for some EQ. I have seen SSF's in the form of an RCA plug, but have heard of no one using them. This would be cheaper and easier for me, but I don't know if it is the best choice.Have you already built the sub and tried the EP2500 with your receiver?
By the way, the ED model is roughly the same price. Any reason for that one over the Reckhorn?