there's no need to install pavucontrol but all i need to do is set up alsamixer to make the audio work

If you want to fiddle the audio at the ALSA level

the hardware

you can, but my guess is that in 2025, unless you have some kind of exotic need, what you probably want is for PipeWire to be setting the volume.

On my system, I use pavucontrol and pipewire-pulse

using pavucontrol doesn't entail using PulseAudio. If you really know what you're doing and you're confident that you want to go bare ALSA, then you can probably go have systemd run a script at boot to run an alsactl restore command. I am pretty confident that that's not what you want to do.

It looks like there's a native console PipeWire mixer in Debian in the form of pipemixer, and I'd imagine that KDE Plasma probably has some sort of graphical mixer that either can talk natively to PipeWire or uses the pipewire-pulse PipeWire emulation of PulseAudio.

EDIT: Basically, you probably want:

------------  
|Sound Card|  
------------  

------------  
|   ALSA   |  
------------  

------------  
| PipeWire | <- You interact with the audio stack at this layer  
------------  

EDIT2: You should probably see that a user-level pipewire is running if you log into your KDE environment and open a virtual termainal and you run:

$ systemctl status --user pipewire.service  

It should say something like:

Active: active (running) since Tue 2025-09-02 00:27:11 PDT; 1 week 6 days ago  

If you have the PulseAudio emulation support active, then ditto for:

$ systemctl status --user pipewire-pulse.service  

I don't use KDE, so I don't know what the KDE mixer program is called or does, whether it talks natively to PipeWire or uses the PulseAudio interface, but KDE Plasma probably puts some sort of volume control in a system tray or something. And it'll probably use one of those two APIs to talk to PipeWire.

EDIT3: Basically, the only times I'd have been wanting to run things through ALSA directly were:

• When it was introduced but before any standardized sound server was deployed, so maybe early 2000s.

• Until JACK and later PipeWire showed up, talking directly to the hardware was a way to keep latency low for real-time processing, so there were some reasons you might want to do this if you were using pro audio.

• Early PulseAudio was pretty broken, so I wound up using ALSA in preference to it.

But that's all pretty much ancient history now.