Same as Archlinux EndeavourOS uses Pulseaudio
PulseAudio is a sound server intended to run as a middleware between your applications and your hardware devices, it is using ALSA or OSS to control audio hardware. The idea is to have an easy way to configure audio for basic needs and also advanced scenarios, it is modular so it screwes down the complexity of alsa configuration to parts more easy to handle.
Pulseaudio is running as a service and socked on per-user level and not systemwide ( Systemd/User ) so service and socket are handled with users-right.
systemctl --user status pulseaudio.socket systemctl --user status pulseaudio.service
Main configuration is
/etc/pulse/default.pa what will be used if user do not create a per user config
~/.config/pulse/default.pa it can rather than being a complete copy,
~/.config/pulse/default.pa can start with the line
.include /etc/pulse/default.pa and then just override the defaults.
But nowadays it can be troublesome on some hardware to get specific stuff working, or simply get sound on the output you want. So if you have an issue read here: