I second Viggen on VenHaus's Power Box. This weekend Lak brought his Flavor 4 power cord (VH uses it in the Power Box) and it outperformed everything else I've had in my system. It is extremely quiet, detailed, with tight, clear, deep bass, clean wide soundstage and no audible bandwith limiting. With the parallel filtration option, VenHaus' box should be something really special...
I've tried the BMI Whale and Shark cords and found them to be easily bested by the Absolute Power Cord ($40). The BMI's are colored, bandwith limiting and bloat the bass. My reference cord has been a Jena Labs cryo'ed Tice PC3 with a Highwire Wirewrap tuning device attached.