When I did my system with Total Contact, in stages due to the time commitment, power cords and AC items made the best improvement, surprisingly. My expectation was that treating the interconnects would make the biggest difference, due to the lower signal strengths.
Cable Goop Review George is going to freak!!
Read it here. http://www.enjoythemusic.com/magazine/equipment/0721/NPS_1260_3D_Enhancer_Solution_Review.htm