Geoffkait 8-13-2017When "the current" is traveling away from the component in one of the two conductors it is traveling toward the component in the other of the two conductors.
Even if one wishes to refer to current as the "signal," since current is alternating we only need to worry about the current (signal) when it’s traveling toward the component or, in the case of speaker cables, when the current is traveling toward the speakers. The other half of the time, when the current is traveling in the opposite direction, we can ignore the "signal" since its effects are inaudible.
And it is **always** traveling through the input circuit of the component in one direction or the other, aside from the brief instant during each cycle at which the applied voltage crosses zero, and the direction changes.
I would not press this explanation as being supportive of wire (or fuse) directionality.
Regards,
-- Al