Cardas Cross power cable - brightness issue

I'm trying out some Cardas Cross power cable. I've had it plugged into my GNSC-modified ARC LS-15 for a week or so. Not a lot of hours on it; maybe 20. Thought it sounded interesting...either opened up the top end a bit, or added some brightness. In listening to some orchestral material the last couple of nights, in the loud parts, the strings didn't sound right...they sounded too top-heavy, too bright. I plugged in my stock cable, and that issue largely disappeared. (I was listening, in particular, to a Deutsche Grammophon recording, which can have a somewhat exaggerated "sheen" on the strings anyway, I'll admit, but it wasn't as noticeable on the stock cable.)

Anybody have any similar experience? Any thoughts about break-in of power cable? I got the idea from somewhere that there was no break-in issue with power cable? Anybody done any comparing among the Cardas power cables, or other power cables compared to Cardas?

Thanks much
Try it on your source instead, weird as it seems when I put some aftermarket powercord on my ARC SP-16 it sounds bright if the source wasn't treated as well. So start at your source, of course IMHO.

I tried Cardas Quadlink 5c power cord and it had rolled off highs, not bright, it was dark and euphonic.
Hey, dark and euphonic, I like that! Seriously, I do. And this is interesting advice. I talked to Cardas as well, and they said I hadn't given it enough time to break in...although someone else said power cord doesn't really have break in time, to speak of.

I'll look into some Cardas Quadlink, too.

Thanks. Any other thoughts out there?
I had one Cardas Cross PC for a year or so. I tried it in different positions, and although it added nothing remotely resembling brightness, the system seemed to have a disparity between the highs and lows. There was a nice midrange, but the highs and lows were totally different, with the midbass on down being thicker and less defined. I blamed it on the Cross PC and sold it. I have since had the same effect, even worse, at different times depending on the combination of ICs, PCs, and power conditioners. Even had the same effect with Golden Reference PCs at times, but with them working great at other times. Perhaps other things contribute to the characteristic (speakers, room, amp), and certain combinations of cables or conditioners exacerbates it. At any rate, it may not have been the Cross PC (otherwise it was pretty good).
I appreciate your thoughts, Glenn. I so far can't really figure out the power cable or power conditioner issue. Although I must say, in general, that one of the frustrating things about high end systems (as I've experienced them) is that I can love my system one day and get annoyed by it the next. It depends a lot on source material, I'm sure...but one of the dealers I've worked with says that tubes just sound a bit different every day...and if he's right...well, I've got a lot of tubes.