The amount of contradictory answers on this thread is mesmerizing.
Yes, you can cure (to a point) brightness by swapping cables, but I would first try a different DAC and see if things get better. Then eventually fine-tune with cables. It makes me laugh when I read "do not use cables as tone controls". Cables have a sound, and you pretty much cannot do without them, so they have to be taken into consideration when you voice a system. It is those who consider cables as mere physical connections without any sonic personality who have it all wrong, and good luck to them achieving what they want.