B-wire - four cables or jumpers?

I have a pair of speakers for which the crossovers are specifically optimised for bi-wiring/bi-amping (Von Schweikert VR5s). As the singal current reaching the speakers comes from an identiscl source, namely the amp teminals, what is the difference between running a second set of cables from the amp, as opposed to using jumpers between the input terminals on the speakers? It seems to my uneducated electronic mind that the only differnce is in the length of the second set, as the signal is merely taken from the speaker terminals, rather than the amp terminals.

If that is so, then what is the sonic (realtime audible) advantage in spending twice the amount of money to run two sets of cables from the amp?

This really puzzels me!