Shed some light on this please

Avguygeorge is right in that you should trust your own ears. My guess at an explanation is that the Pass and Electrocompaniet equipment have much better power supplies than the B&K (as they should, given their pedigree, designers and prices), and you already had some good cables feeding them clean AC to begin with. Look at it this way, you can take the money you were going to spend on new power cords and use it to buy some music for what seems to be a really nice system!

IMHO, the power cord should have little or no effect on a piece of ger with a well designed power supply. If the power supply has a high ammount of filtering, rfi filtering and storage the power cord should have very little effect.

Gmkowal- The engineer part of me would agree with your position. However, having compared power cords on equipment with massively filtered and overbuilt power supplies, has not proven this to be true. I still get quite dramatic sonic improvements with the "great" power cords. Briweve- I think the level of your equipment warrants a higher quality power cord to easily hear the difference over your existing Shunyata's. The Black Mamba is fine, but not really in a class above what you have. The discontinued Shunyata Cobra would be the entry into the next level. However, I'd suggest a Shunyata King Cobra (especially v1) or even better, FIM Gold, to take you into the highest performance level. Then let your ears be the judge. Just my .02. Goodluck.