I agree with Tvad wholeheartedly. Speaker placement and the room itself have the most impact on the perceived brightness apart from your electronics. Cables have the least effect and should only be addressed when you've sort out the rest ie. speaker positioning, room and electronics.
I've just recently got some new speakers and just fiddling around with the placement produced a larger difference than swapping CD players and DAC's.
I've just recently got some new speakers and just fiddling around with the placement produced a larger difference than swapping CD players and DAC's.