Power Cord Upgrade for Inakustik 3500P?

I've been very pleased with the difference in my system I've experienced since adding the Inakustik 3500P. Much blacker noise floor, improved resolution, more headroom, the whole nine yards. My question is whether any owners have tried other premium power cords with the unit, and whether that resulted in much of an improvement?

I am also interested in any feedback on how to get a tighter connection, since heavier cords tend to pull the plug out of the sockets.