I took https://gitlab.freedesktop.org/pipewire/pipewire/-/blob/master/src/daemon/filter-chain/sink-virtual-surround-7.1-hesuvi.conf, and replaced hrir_hesuvi/hrir.wav with the full path to atmos.wav, which I downloaded from https://airtable.com/appayGNkn3nSuXkaz/shruimhjdSakUPg2m/tbloLjoZKWJDnLtTc
Here seems to be a walkthrough of it: https://forum.endeavouros.com/t/virtual-surround-sound-in-pipewire/24958
I also tried jconvolver in the past, but often hit issues when combined with pipewire. Pipewire's native virtual surround support just works when configured correctly.
You can change the default sink to go to the virtual surround device this way:
pactl list short sinks # get sink name
pactl set-default-sink <set default sink>
There will be a way to set the default in the pipewire config files (~/.config/pipewire/pipewire.conf.d/*), too.
I use "catia" when I want to do manual audio routing, and I guess similar is possible with pavucontrol.