Either my ears need checking or my knowledge isn't enough to tell the difference. I hear the samples posted here, checked the streamed video and even tested a night build to hear it by my own. First I was "oh! it sounds better... Wait a minute, does it really? Isn't it a placebo effect just because some else told me it sounds better?". It doesn't help the time span between both comparatives are seconds too apart, I can't turn up the volume loud enough to fight ambient sound and I don't have headphones right now, so everything is my fault.
It looks like this article holds the hint so I'll read it later. Yet, I wish I could know what I am looking at to tell the QSound nor Street Fighter Alpha 2 intro sound better with that feature enabled.