Cannot play headphones and speakers together consistently

Just installed Manjaro, and having a few issues with my audio. First thing first:

$ inxi -Axxx                                                                                                                                                                                                                                                                                                                                                                   
Audio:     Device-1: NVIDIA GA102 High Definition Audio vendor: driver: snd_hda_intel v: kernel bus-ID: 2b:00.1
           chip-ID: 10de:1aef class-ID: 0403
           Device-2: Advanced Micro Devices [AMD] Starship/Matisse HD Audio vendor: Micro-Star MSI driver: snd_hda_intel
           v: kernel bus-ID: 2d:00.4 chip-ID: 1022:1487 class-ID: 0403
           Sound Server-1: ALSA v: k5.15.2-2-MANJARO running: yes
           Sound Server-2: JACK v: 1.9.19 running: no
           Sound Server-3: PulseAudio v: 15.0 running: yes
           Sound Server-4: PipeWire v: 0.3.40 running: yes

I want to have my audio played simultaneously by both the headphones and the speakers connected to the Realtek device (the motherboard). In Windows the audio is correctly routed through both the jacks, so I can listen simulatenously to both speakers and headphones, and I can manually set the volume on both oh them.

In Manjaro, instead, only the headphones is actually bringing out audio, while the speakers are mute. I downloaded pavucontrol and there I can see that for the Realtek card I have Headphones plugged in and Line Out plugged in. This is the first strange thing: shouldn’t it be a Speakers output rather than a Line Out?

Second thing is that selecting Line Out it doesn’t allow me to raise the volume, since it’s locked (but maybe this is because it’s a line out?).

I can open alsamixer and manually unmute the Front volume, but as soon as I disconnect the headphones it mutes again (and please not the Auto-Mute is disabled). Reconnecting them plays audio again but only through headphones, so that the front is mute again and I have to open alsamixer again to unmute it.

What could I be missing?