I'm new to audio DIY and I assumed that wire testing of elements to choose the best op-amp in smd enviroment, were resistance of few ohms and capacitance difference of couple of pico-farrads on wires, which are also acting as antenna makes a difference. But obviously it was my poor modding skills made the sq bad as you noticed.
My modding skills are completely fine actually the only problem is I have trouble with attention to details. Because it isn't cMoy breadboard build anymore I prefer not to make any mistakes and not to choose the ic that cannot be rolled to many times carefully.
Re:1 I'm not new to modding/building/repairing, I've fixed and modded tones of PC's and consoles (that's including reballing bga chips when I was doing this for living), but I'm completely new to DIY audio. I've build my first kind-o-cmoy 4 months ago with opamp I found on old tv pcb when I was bored. But as I've said sometimes I make stupid mistakes.
Re:2 I damaged it because I wasn't careful when taking off "the test wire installation" (lack of attention)
You must have access to oscilloscopes then? I'm sure you can design a test amplifier circuit where you can measure the impact a wire can have on the entire design. Have the oscilloscope point between the two outputs and see for yourself if the wire did any damage for your circuit. My experiences with this is that there is no impact of introducing a wire whatsoever to an amplifier circuit.