Night and day speaker connection

There is a simple explanation for this. You have effectively doubled the gauge to all the drivers with speaker cable. Imo the change is not primarily due to moving to use of a jumper, but by supplying the entire works with double the speaker cable. 

When you split the bi-wire cables, you had half the gauge going to each set of posts. Now, you have doubled the gauge to the speaker via speaker cable. That is a huge difference in performance and is imo the greatest reason for the improvement. 

I always do that when I use jumpers, that is, use a pair of speaker cables to the preferred set of posts for the input. You can reverse it and remove one set of cables from the posts, and you will have a diminishment of the performance globally. 

And now, the coup de grace, are you ready? There is a superior option better than what you just did. It would involve four pair of speaker cables, yes, double bi-wired. It is another step above doubling a set of cables with jumpers. Most would not do this because of cost/availability of cables. However, if I am not mistaken, you have plenty of cables. ;) 

You are correct; the quality of the jumpers is very important. :)

audiosens, I would think that there will be a noticeable difference between what you did and my proposal to double the speaker cables. Whether it would be as profound perceptually as the former, who can say? That is why we have to try things. You will likely have a strong preference for one or the other.

That being said, given enough variety in jumpers I could make any given single pair of speaker cables with the right jumpers outperform any given double pair of speaker cables. It's not that hard to do, however, you need an assortment of wires and the motivation to compare. Most people do not have the goods available, or they are too lazy to try. 

audiosens, yes, just keep trying iterations of cables to the speakers; it is the only way to find the optimum result. That, however, does not assure the best performance from the system. In order to achieve one's best for an entire system all cables in all positions must be considered and tried. I usually recommend trying at least 3 different power cords, USB cables or dig. coax (SPDIF), interconnects, etc. 

That is far more work that most audiophiles are willing to put into it. But, it is the only way to purposefully move toward a better result. Actually, the best way is to compare entire sets of cables and then tune, but that is way beyond the capacity/effort of most audiophiles.