Well, technically speaking, if you are working at 44.1, your converters are not outputting anything over 20k. In fact they are probally starting rolling off anything over 18k.
the human range or hearing is 20hz to 20k (perfect hearing), and that is a VERY VERY good hearing. as we get older, we lose the ability to hear higher frequencies.
I guess my point is that you are saying that you have freak of nature hearing, something almost un-humanly possible, I think you are mistaken as far as what you can hear, and I am only brining this to light, in as if you start making statements of hearing 25k frequency wise here or anywhere, It may impact your credibility.
I studied audio, do music full time, which means nothing really only to say that i feel I have a pretty good basic understanding on audio and frequencies and just what is going on and use them on a daily basis, as do you I am sure. None of my EQ's in pro tools go beyond 20k, and its not neccesary. Even at higher frequencies, the only way I say we can hear it is that most likely its set as a shelving eq, meaning it will effect more then the target frequency, like if I have my eq set to raise 16k, it most likely is raising frequencies much lower then that, and as a result I can maybe hear "air", nothing I woudl say is sonically important.
http://download.npr.org/anon.npr-mp3/atc/atc_teenbuzz.mp3
This is a sound sample at around 14k I believe. Very high and annoying, some adults can't even hear it. Test tones anywhere around 18-20k, most likely will just cause sort of an irritation, rather then anything pleasing or very notible.
Thanks for your input though.