What the...have I just done ? Please explain...


Hello to you lovely sound profis - in my recent attempts in pursuing a great ( or correct as much as it can be ) sound I again started to play with speaker connection vs speaker cable. As I really think this is the gist of my system set up - and I think I was actually correct - but why the result is so good , no clue. Ok so to sum up. I have a speaker cable "Atlas Hyper 2.0" which I have deemed really good and used it in many set ups - after so many changes I came to the point that actually the sound problem lies within speaker cable impendance vs speaker terminal impendance (?) And now something silly that made this question to you:

A few days ago I cut a small 5 cm piece of sticking tape and wrapped it around tight on of the "+" banana jack on the cable ( upper part of the banana jack other 3 jacks are untouched ) then I inserted this jack into the banana terminal in speakers ( they are monitor speakers with biwirable links - all posts are gold plated ) - The sound has been dramatically changed for the better - I mean better imaging and treble response - you can trust me as I am an analytical listener being in Hi Fi many years - what the hell have I just done from the scientific point of view ? If that helped should I replace the speakers posts with plastic covers or choose a speaker cable with increased (?) resistance - or thinner / dicker cable ? Please explain why this trick has improved the sound so much ?

P.S. Thank you in advance , I know this is silly a bit but that really works... :)
audiodav
“ lay off the likker.......”

What he said.....
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This is why I only got a B in Electromagnetic Waves undergrad.
@roberjerman - Yes banana plugs, not jacks , sorry.

@others - Maybe we should leave this topic - I think we won't come to a right conclusion on this one. It's not just that I am a bored musician and came up with something insane - it's simply something with Cable specifications I think. I have no clue why changing or isolating anything an the back of the terminals changes SQ - I think it is unsolvable in this case. At the beginning I thought that the speakers have very instable impedance shifts but I got no clue why isolating ends of the cable improves that. Thank you anyway. 
P.S. 
http://https//german-highend.com/en/infos/cable-voodoo/

"In the stereo application with cinch plugs, new problems arise with the spatial separation of the ground leads (L / R) of the 2 cables, which do not exist with the 5-pin DIN connector with a ground pin and common screen for both channels. If the cables are apart, the ground lines form a loop, into which foreign alternating magnetic fields, e.g., hum, or causing high frequency interference. "