[Implicated]

I think you're missing his point entirely. The problem with these retail purifiers is that you either get quiet or effective. You don't get both.

Sure, you can't hear it from 10ft away - but how much air is it moving at that setting?

I have various configurations of these PC fan setups and the Arctic P14 Pro that you can get 5 for $32 on amazon are honestly wildly effective and designed for applications with some static pressure (radiators and such).

So we're back to; effective or quiet, you're only going to get both with the PC fans, for now.

[tyre]

I have the one I linked and it is both. Set to auto, it is quiet most of the time and only ramps up when I’m cooking or the air quality is bad.

[tguvot]

there is also added benefit of not taking half of the room. i think conway footprint is 1/6th of The Cube if not less.

Rabbit Air (i think they closely related to conway) you can hang on the wall as art piece.