In terms of the filters, I can hear slight differences, but I couldn't say that one actually improves the sound, they just sound different, and after a few seconds, I can't hear the effect anymore. It's kind of like the music shifts slightly when a new filter is applied, but the shift is so slight it doesn't impact the ability to hear clearer, and the effect fades quickly. I do think that unltrasonic ringing can effect the audible portions of the music in the same way that a rock thrown in a pool at one side will change the waves of the pool in the other side, even if you couldn't see the original splash.
I will say that I thought the brick wall filter sounded a little bit crisper in the highs, and I liked it on stuff that needed a bit of extra sparkle - heresy I know, we are supposed to hate brickwall filtering
But overall I have been using the Apodising filter most, it sounds slightly more smooth? But really if I leave on any filter on for a while, I don't notice it's characteristics at all, and if I switch to another, after a minute I don't notice anything about the sound that sticks out as an improvement. Different is not always better.