I just swapped out Groneberg power cords with Volex on my CIA D200's The difference is very nice. Music seems more real, everything tightened up considerably, and detail is better. I tried the Volex cords a couple of months ago, but they seemed to make the music too bright for my taste. The Gronebergs tamed the brightness producing more of a warm sound.
Lately my system has seemed a little too warm and laid back for me with loose bass, so I thought I would give the Volex cords another try. I'm glad I did. They pretty much improved everything across the board with no negative effects.
My system:
Salk HT3
Modwright SWL 9.0SE
RWA SB3
Reality IC's and speaker cables
CIA D200