Speaker jumpers

The stock jumpers on my speakers are precisely where they belong, in a drawer.

IMO; it's a crap shoot and could be very system and listener dependent.
You have to try it for yourself and determine what sounds best. With that said, the vast majority of the time when I espermiented with different systems and speakers (although I have not listened to the 805 Diamonds)
good quality speaker jumpers won the contest.

Yes, the engineers who designed your expensive speakers don't know how to build jumpers.

The best jumpers are the Mega-Magics from Confirmation Bias Cable Co.

the engineers certainly know how to build great jumpers, but the manufacturer often doesn't want to add the cost, and figures you might change them anyway, so some are junk, some are decent...I prefer jumpers identical to my speaker cables...

often the same for power cords too, they figure you will use a different one anyway, so why pay to include a real good one...