Looking for a speaker cable with a relaxed sound.

Cables are no different when it comes to system synergy. You need to balance everything out.

Not like that. If something is too forward, bright, rolled off, dull- you name it, whatever, does not matter - you suck it up. You live with it. Make the best of it. Because nothing is perfect. Everything has its faults. Its hard enough to find something with the least objectionable faults. The absolute last thing you should ever want to do is deliberately go looking for faults. Which is what you're talking about. Its a recipe for failure.

What makes you so sure its the speakers that are the problem? Or more to the point, that laid back cables are the solution? Buying one thing with a problem trying to offset another thing with a problem has never seemed a good solution to me. Only thing worse is if you mis-identify the problem. So, why do you think this is the way to go?