Why even bother with jumpers? Pull the speaker terminal plate, connect them internally, close it back up. If you want to sell some day another 5 min worth of soldering and they're back the way they were.
Right. And your choice of flux. Which isn't required but when you use it and see how sweet it is....
If yours is like the photo on-line a couple screws and the terminal mounting plate pulls out. Look around inside. Often times the crossover is zip tied to a piece of MDF. There should be enough slack for the stock wire to reach. Or if not then to move the crossover enough to reach. Then, not that this is necessary but as long as you're in there, if it is the normal choke and cap strapped to MDF then its pretty easy to improve by putting the crossover board on cones. Or whatever. The crossover sits inside the highest vibration environment in all of audio. Just about anything you do will be an improvement!
Soldering it like this will be a lot better than any jumper you could buy. Heck you could even solder the speaker cable directly, plug the hole and set the whole terminal plate aside for in case you eventually want to sell the speakers.
I went to solder the high frequency leads directly to the low frequency binding posts last night and found the wires are terminated with a female flat spade connector which slides onto the male spade tab that is clamped/nutted to each binding post. I'm not inclined to cut and solder the leads on.
So you found out they used the cheapest fastest crappiest connector and want to leave it that way, in order to spend more money on the best wire in order to have it connected to the crappiest sounding connector. Is that right?
Are you sure?
I have yet to see one of these things that couldn't be removed by pushing a nice sharp pick into the crimp and prying it open. With the wire out you solder it and then if you want to keep the crappy connector for the next guy tape it inside there somewhere.
Just realize you're looking at a situation that for absolute dead certain could be improved more with some Total Contact on the connectors than you could ever get from any jumper.
Once again I am amazed at how cheap parts are used in expensive components. Mods rule.