About the 45kHz thing. There are people in the world that believe that even though the human ear can not hear above 22kHz, a speaker that can play to 45kHz still sounds better. Sounds like a load of audiophile crap to me, but I have never experienced it. One speaker I can think of that does it can be found here:
http://www.focal.tm.fr/gb/home/utopiabe/microbe.htm

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