Even with perfect pitch, the notes would still sound different from one another. That is voicing. So try to get speakers that are matched, especially across the front. The rears are important, but most of the sound comes across the front three, so they must blend well. You don't want one character's voice to change every time it shifts from speaker to speaker.
Cables can affect the sound, true, but be careful.
The fishing wire sometimes included should be discarded at once, but don't go overboard unless you know what you are doing. Spend a bit for a slightly heavier gauge, especially for long runs. Beyond that, though, it gets tricky. A universal, learning remote control can greatly simplify your life. The difference between using five remotes or one macro on one remote is great and is hard to put a price on.