The default might be pointing to the wrong one.
You can see your default device in /dev/sndstat
> cat /dev/sndstat
Installed devices:
pcm0: <NVIDIA (0x0093) (HDMI/DP 8ch)> (play)
pcm1: <NVIDIA (0x0093) (HDMI/DP 8ch)> (play)
pcm2: <NVIDIA (0x0093) (HDMI/DP 8ch)> (play)
pcm3: <NVIDIA (0x0093) (HDMI/DP 8ch)> (play)
pcm4: <Realtek ALC1220 (Rear Analog 5.1/2.0)> (play/rec) default
pcm5: <Realtek ALC1220 (Front Analog)> (play/rec)
pcm6: <Realtek ALC1220 (Rear Digital)> (play)
pcm7: <vendor 0x046d HD Pro Webcam C920> (rec)
No devices installed from userspace.
If you are unsure which one is right, you can set it using the sound preference. You can find it on the speaker icon of the panel.
