you probably need this to find details for the Asus card
lspci -vvnnd "::0401"
(or else “::0402”)
I use my Xonar Essence STX exclusively
The audio card may work better if it is the only device available for system, or the first available device ahead of the HDMI audio
create a file with a text editor (any text editor will do but Manjaro has nano on every DE)
sudo nano /etc/modprobe.d/alsa-cards.conf
add this text to the file to remove the HDMI audio
blacklist snd_hda_intel
Or this to keep the HDMI, but relegate it to 2nd device
options snd slots=snd_virtuoso,snd_hda_intel
use Ctrl + O to save file
and Ctrl + X to exit nano
then reboot to get audio devices reloaded