Well I found I could change the tone but the change I obtained was never better, just different. I was trying to tame the higher frequencies of some speakers without really impacting the overall balance. Didn't work but it did, ultimately, lead me to my conclusion that KISS was the best theory. Problem is that now most speakers have dual connectors and I'm left with the jumper issue. FWIW, I have a good family friend who is an Astro physicist (NASA consultant!) and we got to discussing the issues involved in cabling in an audio system (he's not and audiophile) and it was his stressing of the importance of proper connections, etc, that influenced my thinking. If I were really anal about this I would remove the conectors and go in and hard wire the cables. But in my real world I just accept the issue of using jumpers. Just find the cables that sound the best with your stuff.
BTW, I note that you are using Belden cables from BJ. I assume 10ga. Good stuff and inexpensive. However, as an alternative if you want a cleaner (or brighter) tonal balance you might try some of the Mogami wire. Its very different and also inexpensive. Its interesting to note that both the 10ga Belden and the 10ga Mogami are multistrand twisted wire. The Belden wires are thicker and the Mogami wires are thinner, and I believe there in lays the reason for the tonal balance differences. Get a pair for the fun of it and you can even try the mix and match I referred to earlier.