JoelSim:
If you put the 6mm copper speaker cable that I've mentioned umpteen times now, against the QED Silver Anniversary XT then I would suggest that 100% of people would be able to tell which was playing 100% of the time. The reality of the testing procedure you would have to go through would make this test very hard to perform.
Er the 6mm copper was 6mm thick, the QED very thin, about 2mm I would imagine. And how different they made the same system sound.
If QED Silver Anniversary XT is 2mm then it is 14 AWG which should be ok, or if you mean the whole cable not just the core, lower.
Form my limited reading speaker cable may effect sound in the following ways.
thinner > more skin effect, usually only a problem at frequencies way above audible, but overdone could possibly effect treble
thinner > more maxwell effect, improves bass performance
a thin cable can have superior bandwidth but might have too much resistance (since silver has lower resistance than copper in theory it is slightly superior for speaker cables, because the strands can be thinner)
more resistance > possibly less loud and loudness more effected by the speakers impedance which varies with the frequency of sound it is trying to produce. Also depending on amplifier and speaker combination may effect dampening factor, how tightly the amplifier can control the speaker. So sound maybe more coloured by the speaker and amplifiers characteristics.
higher capacitance > possibly more amplifier oscillation especially in some amplifier designs. So sound more coloured by the amplifiers characteristics.
higher induction > very slightly less loud .
dielectric absorption > time-smear distortion at high frequencies, but very unlikely
Effects to the treble are usually more noticeable as they are less masked by other sounds.
So from my limited reading it appears it is possible it sounds different. The most likely causes are slightly superior bandwidth due to being thinner a real but subtle improvement of performance and why multi-stand is better than solid core and multi-strand with individually insulated multiple strands best, or colouring of the sound due to amplifier and speaker characteristics in theory a loss of audio fidelity but some may prefer the effect.
The manufacturer does not provide any technical details of the electrical properties of the cable, gives no measured results and no double blind test findings. It is impossible for me to know if I would be able to hear a difference. It is also impossible to know if any difference heard is due to improved performance or distortion with out measurement.