Cables to use with a KAB Subsonic filter?

After adding a REL sub, I'm getting a low freq rumble from my sub. A friend is going to let me try his KAB RF-1 subsonic filter to see how this works out. I have a couple of questions:
1. Should I insert it between my phono preamp and preamp, or
Should I insert it in my tape loop? Sonically which would be best?
2. Will my choice of interconnects be an important consideration as to use with the KAB? Is there a good, inexpensive interconnect that you recommend for use with the KAB?
In advance, thanks for your input regarding the use of the KAB.
AS far as IC's, if you put it in the tape loop you can use whatever your preference is but if the KAB is put between the TT and the phono pre you will need to keep the cables as short as possible and use very low capacitance cables.