How to properly hook-up a Martin Logan Grotto sub to Parasound pre P5? With vandy 2sig....

Hello,
I would like to know how others are hooking up their ML Grotto sub to the Parasound Preamp P5. I would appreciate step by step instructions, because My sub is not blending well. Do most use the sub controls on the P5 or the ML sub. Thanks so much, I really appreciate any help. Also what are your settings at? I have a pair of Vandersteen model 2sig.