Ahh yes I read through that thread too, couldn't post anything there since my post count is so low and I didn't think it was same users hehe but yeah, you did probably get defective pair of speakers or like you're saying that you're really prone to high freq hiss sound.
I read through entire 3 pages of this thread, forgive me if it was mentioned before. Anyways.... did you ever connect JBL's to proper audio interface? such as Focusrite Scarlett 2i2?
I've owned these speakers for almost two years now, used to have Yamahas HS 8's too, unfortunately they burned...
Im pretty sure, you can find a reputable member at 'for sale' section, who is selling window 7 keys.
Here is one of them.
http://hardforum.com/showthread.php?t=1876000&highlight=windows+keys