I heards the blue thingy and had two immediate responses....

1)  My capped tooth at the front felt like it had had silver foil pressed up against it, giving a metallic taste in my mouth...This was weird as I noticed it the second I entered the room....

2) I thought that the vocals of artists was sweeter and more life like....I wouldnt say it was the biggest change iVe ever heard, but, there was some improvement and (for me) it was centred on vocals..