Best power cords in the $250-$400 range?

I second the VH Audio recommendation. Low noise floor without coloring the sound, softening transients or constraining dynamics. Better cords can make the VH Audio sound a little coarse and can resolve more subtle detail, but I don't know of any in your price range except for scoring a great second hand deal. They are a bit stiff for some very light components, but that goes for most PCs.

I've decided to try a VH Flavor 4 w/gold furutechs for my amp (figure the 9 ga conductors will satisy current draw well). VH Flavor 1 with Rhodium Furutech for my DVD and Flavor 1 with Gold Furutech (figure 12 ga is plenty of conductor for source gear). Buying as demo cords from Chris at VH.

Harshness, graniness in my system has been significantly reduced. Background "blackness" has improved. I would say the sound from my system is now smoother yet more vibrant. I am considering an upgrade from the 2910 to the 3910 to hear if this makes a difference.

I have done a lot of search for under $500 power cords and the most natural one I have found is the Acoustic Zen Tsnami, very solid in all parameters.

#1 make sure you are not running your amp thru the monster center, I would guess you are not, but its a mistake if you are.. I have had them they do not sound as good as straight to the wall.. Also the 3600 has more filtering than the 2600 which restricts audio even further, the 2600 series simply sounds better.. But for connections and video the 3600 is very good. So Put the amp to the wall for sure, and Try out cables from Fatwyre.com ,they got a ton of the big brands and have them used many times as well... Also will take back and send you many until you find the right one.