Looking to buy some new headphones and speakers

[obey_evolution]

Hi, I'm thinking that the effectiveness of silent subliminal content on some of my files might be held back by the quality of my speakers. What is the FULL relevant audio signal range (high and low) for hypnotic subliminal content (including high end silent subliminal). I've see a file with 17 or 18 KHz tones in Audacity which, by Nyquist, means they were likely sampled at 44.1 or 48KHz which are both supported by the MP3 format.
Once I know what dynamic range to look for, I'm going to ask about nice speakers and headphones with that range so I can order some. I'm currently using these which I think should be REALLY good, but I'd like to "see the math".

http://www.bose.ca/controller?url=/shop_online/headphones/noise_cancelling_headphones/quietcomfort_20/index.jsp&Variant=qc20