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
Sticking tape? Sounds more like a crappy contact issue.
Ok but to add now to your answer:

The speaker cable has really good and firm terminations with gold plated banana jacks. The posts on the speakers are very good installed ( Leema Acoustics monitor speakers ) no loose parts either in speakers or with cable.

Do you think that banana jacks have not complete contacts inside the posts ? These are Z plugs. But again - the sticking tape makes the connection even smaller (?)
Audiodav, it has nothing to do with the tape. It is just a bad banana plug. The only banana plugs I will use are the locking type. Regular ones lose their spring and get loose over time. You can take a little flat head screw driver and pry the contacts apart to make a better connection but I would rather put new locking banana plugs on. Parts Express carries them. In terms of speaker cables you want the lowest parallel and series impedance you can get. A very low gauge 10 or lower, tightly twisted pair of the shortest length you can use meets that requirement. Another great design if you want something fancier looking is Kimber cable which you can get in rolls and make your own cables. I use 12 TC. 
Ahhh ok. So it looks like the banana jack contact problem indeed. Right, there are some better locking bananas out there. Super , thank you and the others for your answers. Will do mijostyn and take a look at better connections...with maybe better cable.
Go to Best Buy and get speaker cable for$40 buk ,and avoid the problem
Banana PLUG - not "jack"! The jack is the part the plug goes into. Putting a piece of tape on a plug for an improvement in SQ - lay off the likker, ok?
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“ 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. "
Knukonceptz also offers fantastic banana plugs that are the only ones i could find to accept my 8 guage cable. Excellent contact.
>>>> 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 ) -<<<<
People don't realize that plastics in contact with the metal can alter the sound.   Its how the Ground Zero tweaks work with a controlled effect.  It seems you got your own version of this thing at work...
http://www.wghwoodworking.com/audio/ground_enhancer2.jpg
I am an analytical listener being in Hi Fi many years - what the hell have I just done from the scientific point of view ?
Since when did the perceived results of these kinds of "tweaks" have anything to do with science?
I just re terminated my speaker cables with WBT-0610 cu. locking plugs. Will accept up 6 gauge. There are some similar types Furutech makes some nice ones too
I don’t think that's the same as the Ground Zero tweak at all. That picture is just as you said, plastic on metal with no circuit, and seems like it would have little if any effect. I believe the OP has thru trial and error created a smaller contact area that’s closer to the wires on the other side of the binding post. I had imagined a similar z type connector but with a raised and rolled edge at the end and hard plastic above to accomplish this. The idea is that the metallurgy and geometry of most binding posts are much worse than good speaker wire (unless you use something like WBT nextgen). Additionally, the current would be distributed more uniformly in the circular shape of the post rather than spades where it comes in from one side. This shorter path may be why many prefer spades (along with their better contact pressure). Good experimenting, but watch out for that sticky tape residue that may ruin your conductivity. I’m also surprised the thickness of the tape didn’t impede your connection by lessening the pressure. Did you notice any downsides at all, like loss of bass or dynamics? Oh I see, you did this on biwire, probably the treble +. If anything you might notice a slight hole in the mid-range. Having said all that, I'd still bet on good spades or bare wire for cheaper setups. :)