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... :)