The most detailed speaker cables will be the ones that are fed the most
information by the front end, pre-amp, amplifier and that feed the signal into
speakers capable of resolving that signal into a room that doesn't suppress
the detail because of some problem or another. Speaker cables aren't
detailed, systems are detailed. If you're not getting enough detail, it is
unlikely the cables are causing this problem.
If you hear "brightness" as more detail, get an equalizer and bump the high
end. You'll have more control over your sound than you will by fishing
around hoping to find a pair of speaker cables that will bump the high end.
If you want a tone control, why not get a tone control? For the same price as
you pay for Acoustic Zen Sartori's, I've got to think you could get a hell of a
graphic equalizer. There are some that can analyze and help solve problems
in your room and give you the ability to make very small adjustments in
narrow portions of the audio band.
Why use a cable for a tone control when it gives you such little control -- IF
you can find one that bumps the part of the audio band that you favor to the
extent you find pleasurable?
With some careful search, you can probably also find speakers that have a
bump in the high end and more than just a fraction of a db, or whatever
you're hoping for from a cable.
Before buying cables hoping they will bump the high end, giving you the
impression you're getting more detail, make sure you get a frequency
response graph proving that the cables in question will give you an audible
bump in the high end. Then, compare the cost of those cables for the effect
you might get versus switching speakers or adding a graphic equalizer.