KAB RF-1 subsonic filter

 I would have thought these very simple instructions would have come with the RF-1 from KAB.

They do. 

KAB recommend install the RF-1 between the phono stage and preamp

I've tried the filter installed here as well as between the preamp and main amp (which is where it currently is), no difference I have been able to discern with vinyl and digital sources sound no different as well. 

That said, just to appease my OCD, I likely will put it back in the phono to pre line as to not have one more variable in the line with other sources.