I've wondered a bit about this myself. The only logical conclusion I can come up with is that the dielectric does change with electrical flow. If this is true (I have no conclusive evidence that it is), then cable break in (which changes the dielectric) should be performed in the same direction that the cable is to be used. Could you go either way and get the same result? In other words use the cable in the reverse direction, as long as you were consistent? I would think so. I have heard (or read) from Synergistic somewhere that they determine the direction by listening to the cable. There are some theories about eddie currents in cables, but I know little about this and would really like to hear from a cable manufacturer. Is the arrow absolute, or just a way to continue to use the cable in a consistent manner? In other words, are we dealing the dielectric effect or the actual wire?