alright. i just got out my filco brown, just for you, to test what i had typed out and erased.
first of all, i dont think comparing audio clips is valid for VOLUME. type of sound, maybe, sort of, but not volume.
im sitting here with my HHKB and filco. everything i have typed in this post with my HHKB i am typing on the disconnected filco, after each sentence.
im telling you, the noise level is not really comparable. the topre switches emit a lower, more unique sound... like wooden sticks clacking together. when i bottom out, just a very quiet 'thud'. supposedly a lot of the topre sound comes from the usually-POM keycaps, and i believe it, they have a great deal of influence on the feel.
now for the brown. a much 'lighter' sound, but not to say it is 'sharper'. just has much more of a 'typewriter' sound to it. sounds a lot more 'mechanical'. when alternating keyboards typing a part down below, i guessed that it sounds more like rain on a rooftop. when you bottom them out, you get a second noise with each keypress, but it much quieter and more subdued than the first. when i type fast it sounds more rhythmic, and less like many individual sounds like the topre does. the exception to this rhythm is the spacebar. though the topre spacebar is louder than the rest of the keys, it is also a deeper note. the brown (at least, on my filco remember) is a louder, sharper noise that can be picked out from the rest, as if you can hear when each word starts and ends. i feel like a lot of this is due to the relatively thin, flimsy plastic of the filco keys, like it is rattling under my thumb, so maybe it is something that can be trained to be reduced.
not trying to sway you either way, but if pure silence is all you are looking for, i dont think the topre is really offering anything more for twice the price. i know you are using the audio clips to try to gauge it, but i wouldnt really trust those as a real comparison. not that you should trust me either. but realistically i think a quiet rubber dome (my G15, for example) is quieter than either.
and yes, this comes from a topre bottom-outer (though i dont think i do it every single stroke, lately, but it is certainly not due to feeling any sort of 'bump'), and a gifted soul that can not bottom out the browns... but again, i am not the only person to have these tendencies.
EDIT and dont feel too bad,
my search for the one and only keyboard that was quiet and not clickety-clackety went on for a lot longer. and now i actually own clicky keyboards. not sure if i like them yet, though.