You shouldn't hear any difference with or without these. Brands don't matter, gold sounds just as good as Nickel- it's all marketing BS. Banana plugs were invented for use when the connections are changed frequently, as I already mentioned- design engineering, test laboratories, displays and usually anything BUT the common consumer installation. They can be helpful when the wires can't be made longer but still reach the terminals, though- when that happens, it's much easier to use right angle banana plugs than trying to tighten the binding posts.
Using any kind of plug adds connecting points and therefore, points of failure. Also, the screws can loosen over time. They shouldn't, but they do. That can cause the wires to fall out and possibly, touch. When that happens, kiss the amplifier goodbye.
Using gold plugs etc and expecting an improvement makes absolutely no sense- it's like using a hospital grade outlet on power wiring that has been in place for decades, hoping that the sound will improve because somehow, the power is now 'cleaner' when those outlets have no filtering or any other way of making ANYTHING better.
I think you might want to stop looking for ways to spend money and enjoy your system. If you can prove something is bad, repair or replace it, but searching for tiny improvements that aren't likely or possible is neurotic.
If the wires are too short to reach the speaker's terminals, splice it, but do it properly. That flies in the face of EVERY audiopile, but I don't care, it's not only necessary, it works just fine. There are literally millions of buildings where wires were spliced and nobody notices. These are often installations where reliability is critical, yet it has been done over many decades. I have worked for some of the contractors who do this and I also did car audio for a long time- if you don't think competition car audio systems have zero splices and unnecessary connectors, guess again.