it seems xfce depends on PA

Yes, that has been discussed before: https://dev1galaxy.org/viewtopic.php?id=2545

aptitude why pulseaudio

erdos@devuan:/etc/X11$ aptitude why pulseaudio
i   task-desktop      Recommends task-xfce-desktop | task-cinnamon-desktop | task-kde-desktop
                                  | task-lxqt-desktop | task-mate-desktop                   
i A task-xfce-desktop Recommends gnome-orca                                                 
i A gnome-orca        Depends    speech-dispatcher (>= 0.8)                                 
i A speech-dispatcher Recommends pulseaudio

I use 'xfce' as DE, it seems xfce depends on PA

apt-get purge pulseaudio

Note that if you remove pulseaudio you MUST purge it. Otherwise configuration files are left behind that break alsa.

Pulseaudios default settings are fine for most users. I honestly wouldn't worry about it unless it gives you problems.

With my desktop hardware, a 44.1 khz sampling rate gives me noise issues. All my audio needs to be re-sampled to 48 khz. With pulseaudio the latency is too high, and the re-sample quality could be better. When I tried bringing down the latency and increasing the re-sample quality the resource usage increased significantly. Alsa doesn't give me those issues, and I find the configuration files significantly easier to understand and modify.

My ancient laptop also performs better without pulseaudio, and I suspect others with older devices would benefit from a pure alsa setup as well.

if FF default to use PA?

The firefox-esr package in ASCII can produce sound without PA but if PA is running then it will use it.

See what's invited PA to your party:

aptitude why pulseaudio

You may have to continue down the dependency chain for a bit.

If you can't remove the PA package then you can try to stop it from starting, for example: https://kodi.wiki/view/PulseAudio/HOW-T … for_Ubuntu

You may have to also copy the pulseadui.desktop file from /etc/xdg/autostart/ to ~/.config/autostart/ and add Hidden=true to the end of the file.

Alternatively, keep PA installed & running and use pavucontrol to set the default output device.

I've seen several forum members claim audio sounds better with pure ALSA but I am strongly of the opinion that this is just confirmation bias. [/troll]

it's strange because i installed devuan last night and at first i don't remember seeing PA settings in volume control, i've installed Kodi afterwards, maybe Kodi pulled in PA as dependencies.  but FF definitely had no sound before installing kodi, if FF default to use PA?

and how do i use ALSA instead of PA in ascii?

youtube has no sound on a fresh install of ascii and firefox (68.4-1 esr)

erdos@devuan:/etc/X11$ amixer
Simple mixer control 'Master',0
  Capabilities: pvolume pswitch pswitch-joined
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 65536
  Mono:
  Front Left: Playback 65536 [100%] [on]
  Front Right: Playback 65536 [100%] [on]
Simple mixer control 'Capture',0
  Capabilities: cvolume cswitch cswitch-joined
  Capture channels: Front Left - Front Right
  Limits: Capture 0 - 65536
  Front Left: Capture 5730 [9%] [off]
  Front Right: Capture 5730 [9%] [off]
erdos@devuan:/etc/X11$ amixer set Master 50%
Simple mixer control 'Master',0
  Capabilities: pvolume pswitch pswitch-joined
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 65536
  Mono:
  Front Left: Playback 32768 [50%] [on]
  Front Right: Playback 32768 [50%] [on]

any ideas?